* nscd/nscd-client.h (__nscd_cache_search): Remove const qualifier

from return value. 
* nscd/nscd_helper.c: Include string.h. 
(__nscd_cache_search): Remove const qualifier from return value. 
On strict alignment architectures check hash entry and data head 
alignment. 
* nscd/nscd_getpw_r.c (nscd_getpw_r): Don't crash or fail because 
mmapped data during GC cycle contains garbage.  If 
__nscd_drop_map_ref fails, decrement mapped->counter when returning 
error or if retrying with NO_MAPPING, only __nscd_unmap if counter 
dropped to 0. 
* nscd/nscd_getgr_r.c (nscd_getgr_r): Likewise. 
* nscd/nscd_initgroups.c (__nscd_getgrouplist): Likewise. 
* nscd/nscd_gethst_r.c (nscd_gethst_r): Likewise. 
* nscd/nscd_getai.c (__nscd_getai): Likewise. 
* nscd/nscd_getserv_r.c (nscd_getserv_r): Likewise.
2007-01-31  Jakub Jelinek  <jakub@redhat.com>

	* nscd/nscd-client.h (__nscd_cache_search): Remove const qualifier
	from return value.
	* nscd/nscd_helper.c: Include string.h.
	(__nscd_cache_search): Remove const qualifier from return value.
	On strict alignment architectures check hash entry and data head
	alignment.
	* nscd/nscd_getpw_r.c (nscd_getpw_r): Don't crash or fail because
	mmapped data during GC cycle contains garbage.  If
	__nscd_drop_map_ref fails, decrement mapped->counter when returning
	error or if retrying with NO_MAPPING, only __nscd_unmap if counter
	dropped to 0.
	* nscd/nscd_getgr_r.c (nscd_getgr_r): Likewise.
	* nscd/nscd_initgroups.c (__nscd_getgrouplist): Likewise.
	* nscd/nscd_gethst_r.c (nscd_gethst_r): Likewise.
	* nscd/nscd_getai.c (__nscd_getai): Likewise.
	* nscd/nscd_getserv_r.c (nscd_getserv_r): Likewise.

9 files changed, 387 insertions, 245 deletions

diff --git a/ChangeLog b/ChangeLog
index dff9ca56ba..1e7631f946 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,22 @@
+2007-01-31  Jakub Jelinek  <jakub@redhat.com>
+
+	* nscd/nscd-client.h (__nscd_cache_search): Remove const qualifier
+	from return value.
+	* nscd/nscd_helper.c: Include string.h.
+	(__nscd_cache_search): Remove const qualifier from return value.
+	On strict alignment architectures check hash entry and data head
+	alignment.
+	* nscd/nscd_getpw_r.c (nscd_getpw_r): Don't crash or fail because
+	mmapped data during GC cycle contains garbage.  If
+	__nscd_drop_map_ref fails, decrement mapped->counter when returning
+	error or if retrying with NO_MAPPING, only __nscd_unmap if counter
+	dropped to 0.
+	* nscd/nscd_getgr_r.c (nscd_getgr_r): Likewise.
+	* nscd/nscd_initgroups.c (__nscd_getgrouplist): Likewise.
+	* nscd/nscd_gethst_r.c (nscd_gethst_r): Likewise.
+	* nscd/nscd_getai.c (__nscd_getai): Likewise.
+	* nscd/nscd_getserv_r.c (nscd_getserv_r): Likewise.
+
 2007-01-30  Ulrich Drepper  <drepper@redhat.com>
 
 	* misc/hsearch_r.c (hdestroy_r): Remove unnecessary test.
diff --git a/nscd/nscd-client.h b/nscd/nscd-client.h
index 7702f590bd..051a262c3e 100644
--- a/nscd/nscd-client.h
+++ b/nscd/nscd-client.h
@@ -323,10 +323,10 @@ static inline int __nscd_drop_map_ref (struct mapped_database *map,
 
 
 /* Search the mapped database.  */
-extern const struct datahead *__nscd_cache_search (request_type type,
-						   const char *key,
-						   size_t keylen,
-						   const struct mapped_database *mapped);
+extern struct datahead *__nscd_cache_search (request_type type,
+					     const char *key,
+					     size_t keylen,
+					     const struct mapped_database *mapped);
 
 /* Wrappers around read, readv and write that only read/write less than LEN
    bytes on error or EOF.  */
diff --git a/nscd/nscd_getai.c b/nscd/nscd_getai.c
index b59c31ea26..5df32dc6dc 100644
--- a/nscd/nscd_getai.c
+++ b/nscd/nscd_getai.c
@@ -1,4 +1,4 @@
-/* Copyright (C) 2004, 2005, 2006 Free Software Foundation, Inc.
+/* Copyright (C) 2004, 2005, 2006, 2007 Free Software Foundation, Inc.
    This file is part of the GNU C Library.
    Contributed by Ulrich Drepper <drepper@redhat.com>, 2004.
 
@@ -42,6 +42,7 @@ __nscd_getai (const char *key, struct nscd_ai_result **result, int *h_errnop)
 {
   size_t keylen = strlen (key) + 1;
   int gc_cycle;
+  int nretries = 0;
 
   /* If the mapping is available, try to search there instead of
      communicating with the nscd.  */
@@ -50,49 +51,53 @@ __nscd_getai (const char *key, struct nscd_ai_result **result, int *h_errnop)
 			       &gc_cycle);
 
  retry:;
-  const ai_response_header *ai_resp = NULL;
   struct nscd_ai_result *resultbuf = NULL;
   const char *recend = (const char *) ~UINTMAX_C (0);
   char *respdata = NULL;
   int retval = -1;
   int sock = -1;
+  ai_response_header ai_resp;
 
   if (mapped != NO_MAPPING)
     {
-      const struct datahead *found = __nscd_cache_search (GETAI, key, keylen,
-							  mapped);
+      struct datahead *found = __nscd_cache_search (GETAI, key, keylen,
+						    mapped);
       if (found != NULL)
 	{
-	  ai_resp = &found->data[0].aidata;
-	  respdata = (char *) (ai_resp + 1);
+	  respdata = (char *) (&found->data[0].aidata + 1);
+	  ai_resp = found->data[0].aidata;
 	  recend = (const char *) found->data + found->recsize;
+	  /* Now check if we can trust ai_resp fields.  If GC is
+	     in progress, it can contain anything.  */
+	  if (mapped->head->gc_cycle != gc_cycle)
+	    {
+	      retval = -2;
+	      goto out;
+	    }
 	}
     }
 
   /* If we do not have the cache mapped, try to get the data over the
      socket.  */
-  ai_response_header ai_resp_mem;
-  if (ai_resp == NULL)
+  if (respdata == NULL)
     {
-      sock = __nscd_open_socket (key, keylen, GETAI, &ai_resp_mem,
-				 sizeof (ai_resp_mem));
+      sock = __nscd_open_socket (key, keylen, GETAI, &ai_resp,
+				 sizeof (ai_resp));
       if (sock == -1)
 	{
 	  /* nscd not running or wrong version.  */
 	  __nss_not_use_nscd_hosts = 1;
 	  goto out;
 	}
-
-      ai_resp = &ai_resp_mem;
     }
 
-  if (ai_resp->found == 1)
+  if (ai_resp.found == 1)
     {
-      size_t datalen = ai_resp->naddrs + ai_resp->addrslen + ai_resp->canonlen;
+      size_t datalen = ai_resp.naddrs + ai_resp.addrslen + ai_resp.canonlen;
 
-      /* This check is really only affects the case where the data
+      /* This check really only affects the case where the data
 	 comes from the mapped cache.  */
-      if ((char *) (ai_resp + 1) + datalen > recend)
+      if (respdata + datalen > recend)
 	{
 	  assert (sock == -1);
 	  goto out;
@@ -108,10 +113,10 @@ __nscd_getai (const char *key, struct nscd_ai_result **result, int *h_errnop)
 	}
 
       /* Set up the data structure, including pointers.  */
-      resultbuf->naddrs = ai_resp->naddrs;
+      resultbuf->naddrs = ai_resp.naddrs;
       resultbuf->addrs = (char *) (resultbuf + 1);
-      resultbuf->family = (uint8_t *) (resultbuf->addrs + ai_resp->addrslen);
-      if (ai_resp->canonlen != 0)
+      resultbuf->family = (uint8_t *) (resultbuf->addrs + ai_resp.addrslen);
+      if (ai_resp.canonlen != 0)
 	resultbuf->canon = (char *) (resultbuf->family + resultbuf->naddrs);
       else
 	resultbuf->canon = NULL;
@@ -137,10 +142,13 @@ __nscd_getai (const char *key, struct nscd_ai_result **result, int *h_errnop)
 
 	  /* Try to detect corrupt databases.  */
 	  if (resultbuf->canon != NULL
-	      && resultbuf->canon[ai_resp->canonlen - 1] != '\0')
+	      && resultbuf->canon[ai_resp.canonlen - 1] != '\0')
 	    /* We cannot use the database.  */
 	    {
-	      free (resultbuf);
+	      if (mapped->head->gc_cycle != gc_cycle)
+		retval = -2;
+	      else
+		free (resultbuf);
 	      goto out_close;
 	    }
 
@@ -150,7 +158,7 @@ __nscd_getai (const char *key, struct nscd_ai_result **result, int *h_errnop)
     }
   else
     {
-      if (__builtin_expect (ai_resp->found == -1, 0))
+      if (__builtin_expect (ai_resp.found == -1, 0))
 	{
 	  /* The daemon does not cache this database.  */
 	  __nss_not_use_nscd_hosts = 1;
@@ -158,7 +166,7 @@ __nscd_getai (const char *key, struct nscd_ai_result **result, int *h_errnop)
 	}
 
       /* Store the error number.  */
-      *h_errnop = ai_resp->error;
+      *h_errnop = ai_resp.error;
 
       /* The `errno' to some value != ERANGE.  */
       __set_errno (ENOENT);
@@ -170,22 +178,25 @@ __nscd_getai (const char *key, struct nscd_ai_result **result, int *h_errnop)
   if (sock != -1)
     close_not_cancel_no_status (sock);
  out:
-  if (__nscd_drop_map_ref (mapped, &gc_cycle) != 0 && retval != -1)
+  if (__nscd_drop_map_ref (mapped, &gc_cycle) != 0)
     {
       /* When we come here this means there has been a GC cycle while we
 	 were looking for the data.  This means the data might have been
 	 inconsistent.  Retry if possible.  */
-      if ((gc_cycle & 1) != 0)
+      if ((gc_cycle & 1) != 0 || ++nretries == 5 || retval == -1)
 	{
 	  /* nscd is just running gc now.  Disable using the mapping.  */
-	  __nscd_unmap (mapped);
+	  if (atomic_decrement_val (&mapped->counter) == 0)
+	    __nscd_unmap (mapped);
 	  mapped = NO_MAPPING;
 	}
 
-      *result = NULL;
-      free (resultbuf);
-
-      goto retry;
+      if (retval != -1)
+	{
+	  *result = NULL;
+	  free (resultbuf);
+	  goto retry;
+	}
     }
 
   return retval;
diff --git a/nscd/nscd_getgr_r.c b/nscd/nscd_getgr_r.c
index 922b906c19..fc036f2888 100644
--- a/nscd/nscd_getgr_r.c
+++ b/nscd/nscd_getgr_r.c
@@ -1,4 +1,5 @@
-/* Copyright (C) 1998-2000, 2002-2005, 2006 Free Software Foundation, Inc.
+/* Copyright (C) 1998-2000, 2002-2005, 2006, 2007
+   Free Software Foundation, Inc.
    This file is part of the GNU C Library.
    Contributed by Thorsten Kukuk <kukuk@uni-paderborn.de>, 1998.
 
@@ -88,6 +89,7 @@ nscd_getgr_r (const char *key, size_t keylen, request_type type,
 	      struct group **result)
 {
   int gc_cycle;
+  int nretries = 0;
   const uint32_t *len = NULL;
   size_t lensize = 0;
 
@@ -97,55 +99,59 @@ nscd_getgr_r (const char *key, size_t keylen, request_type type,
 						       &__gr_map_handle,
 						       &gc_cycle);
  retry:;
-  const gr_response_header *gr_resp = NULL;
   const char *gr_name = NULL;
   size_t gr_name_len = 0;
   int retval = -1;
   const char *recend = (const char *) ~UINTMAX_C (0);
+  gr_response_header gr_resp;
 
   if (mapped != NO_MAPPING)
     {
-      const struct datahead *found = __nscd_cache_search (type, key, keylen,
-							  mapped);
+      struct datahead *found = __nscd_cache_search (type, key, keylen, mapped);
       if (found != NULL)
 	{
-	  gr_resp = &found->data[0].grdata;
-	  len = (const uint32_t *) (gr_resp + 1);
-	  /* The alignment is always sufficient.  */
-	  assert (((uintptr_t) len & (__alignof__ (*len) - 1)) == 0);
+	  len = (const uint32_t *) (&found->data[0].grdata + 1);
+	  gr_resp = found->data[0].grdata;
 	  gr_name = ((const char *) len
-		     + gr_resp->gr_mem_cnt * sizeof (uint32_t));
-	  gr_name_len = gr_resp->gr_name_len + gr_resp->gr_passwd_len;
+		     + gr_resp.gr_mem_cnt * sizeof (uint32_t));
+	  gr_name_len = gr_resp.gr_name_len + gr_resp.gr_passwd_len;
 	  recend = (const char *) found->data + found->recsize;
+	  /* Now check if we can trust gr_resp fields.  If GC is
+	     in progress, it can contain anything.  */
+	  if (mapped->head->gc_cycle != gc_cycle)
+	    {
+	      retval = -2;
+	      goto out;
+	    }
+
+	  /* The alignment is always sufficient, unless GC is in progress.  */
+	  assert (((uintptr_t) len & (__alignof__ (*len) - 1)) == 0);
 	}
     }
 
-  gr_response_header gr_resp_mem;
   int sock = -1;
-  if (gr_resp == NULL)
+  if (gr_name == NULL)
     {
-      sock = __nscd_open_socket (key, keylen, type, &gr_resp_mem,
-				 sizeof (gr_resp_mem));
+      sock = __nscd_open_socket (key, keylen, type, &gr_resp,
+				 sizeof (gr_resp));
       if (sock == -1)
 	{
 	  __nss_not_use_nscd_group = 1;
 	  goto out;
 	}
-
-      gr_resp = &gr_resp_mem;
     }
 
   /* No value found so far.  */
   *result = NULL;
 
-  if (__builtin_expect (gr_resp->found == -1, 0))
+  if (__builtin_expect (gr_resp.found == -1, 0))
     {
       /* The daemon does not cache this database.  */
       __nss_not_use_nscd_group = 1;
       goto out_close;
     }
 
-  if (gr_resp->found == 1)
+  if (gr_resp.found == 1)
     {
       struct iovec vec[2];
       char *p = buffer;
@@ -157,8 +163,8 @@ nscd_getgr_r (const char *key, size_t keylen, request_type type,
 	 align the pointer.  */
       align = ((__alignof__ (char *) - (p - ((char *) 0)))
 	       & (__alignof__ (char *) - 1));
-      total_len = (align + (1 + gr_resp->gr_mem_cnt) * sizeof (char *)
-		   + gr_resp->gr_name_len + gr_resp->gr_passwd_len);
+      total_len = (align + (1 + gr_resp.gr_mem_cnt) * sizeof (char *)
+		   + gr_resp.gr_name_len + gr_resp.gr_passwd_len);
       if (__builtin_expect (buflen < total_len, 0))
 	{
 	no_room:
@@ -170,16 +176,16 @@ nscd_getgr_r (const char *key, size_t keylen, request_type type,
 
       p += align;
       resultbuf->gr_mem = (char **) p;
-      p += (1 + gr_resp->gr_mem_cnt) * sizeof (char *);
+      p += (1 + gr_resp.gr_mem_cnt) * sizeof (char *);
 
       /* Set pointers for strings.  */
       resultbuf->gr_name = p;
-      p += gr_resp->gr_name_len;
+      p += gr_resp.gr_name_len;
       resultbuf->gr_passwd = p;
-      p += gr_resp->gr_passwd_len;
+      p += gr_resp.gr_passwd_len;
 
       /* Fill in what we know now.  */
-      resultbuf->gr_gid = gr_resp->gr_gid;
+      resultbuf->gr_gid = gr_resp.gr_gid;
 
       /* Read the length information, group name, and password.  */
       if (gr_name == NULL)
@@ -187,17 +193,17 @@ nscd_getgr_r (const char *key, size_t keylen, request_type type,
 	  /* Allocate array to store lengths.  */
 	  if (lensize == 0)
 	    {
-	      lensize = gr_resp->gr_mem_cnt * sizeof (uint32_t);
+	      lensize = gr_resp.gr_mem_cnt * sizeof (uint32_t);
 	      len = (uint32_t *) alloca (lensize);
 	    }
-	  else if (gr_resp->gr_mem_cnt * sizeof (uint32_t) > lensize)
+	  else if (gr_resp.gr_mem_cnt * sizeof (uint32_t) > lensize)
 	    len = extend_alloca (len, lensize,
-				 gr_resp->gr_mem_cnt * sizeof (uint32_t));
+				 gr_resp.gr_mem_cnt * sizeof (uint32_t));
 
 	  vec[0].iov_base = (void *) len;
-	  vec[0].iov_len = gr_resp->gr_mem_cnt * sizeof (uint32_t);
+	  vec[0].iov_len = gr_resp.gr_mem_cnt * sizeof (uint32_t);
 	  vec[1].iov_base = resultbuf->gr_name;
-	  vec[1].iov_len = gr_resp->gr_name_len + gr_resp->gr_passwd_len;
+	  vec[1].iov_len = gr_resp.gr_name_len + gr_resp.gr_passwd_len;
 	  total_len = vec[0].iov_len + vec[1].iov_len;
 
 	  /* Get this data.  */
@@ -209,14 +215,14 @@ nscd_getgr_r (const char *key, size_t keylen, request_type type,
 	/* We already have the data.  Just copy the group name and
 	   password.  */
 	memcpy (resultbuf->gr_name, gr_name,
-		gr_resp->gr_name_len + gr_resp->gr_passwd_len);
+		gr_resp.gr_name_len + gr_resp.gr_passwd_len);
 
       /* Clear the terminating entry.  */
-      resultbuf->gr_mem[gr_resp->gr_mem_cnt] = NULL;
+      resultbuf->gr_mem[gr_resp.gr_mem_cnt] = NULL;
 
       /* Prepare reading the group members.  */
       total_len = 0;
-      for (cnt = 0; cnt < gr_resp->gr_mem_cnt; ++cnt)
+      for (cnt = 0; cnt < gr_resp.gr_mem_cnt; ++cnt)
 	{
 	  resultbuf->gr_mem[cnt] = p;
 	  total_len += len[cnt];
@@ -224,9 +230,25 @@ nscd_getgr_r (const char *key, size_t keylen, request_type type,
 	}
 
       if (__builtin_expect (gr_name + gr_name_len + total_len > recend, 0))
-	goto out_close;
+	{
+	  /* len array might contain garbage during nscd GC cycle,
+	     retry rather than fail in that case.  */
+	  if (gr_name != NULL && mapped->head->gc_cycle != gc_cycle)
+	    retval = -2;
+	  goto out_close;
+	}
       if (__builtin_expect (total_len > buflen, 0))
-	goto no_room;
+	{
+	  /* len array might contain garbage during nscd GC cycle,
+	     retry rather than fail in that case.  */
+	  if (gr_name != NULL && mapped->head->gc_cycle != gc_cycle)
+	    {
+	      retval = -2;
+	      goto out_close;
+	    }
+	  else
+	    goto no_room;
+	}
 
       retval = 0;
       if (gr_name == NULL)
@@ -248,14 +270,14 @@ nscd_getgr_r (const char *key, size_t keylen, request_type type,
 
 	  /* Try to detect corrupt databases.  */
 	  if (resultbuf->gr_name[gr_name_len - 1] != '\0'
-	      || resultbuf->gr_passwd[gr_resp->gr_passwd_len - 1] != '\0'
-	      || ({for (cnt = 0; cnt < gr_resp->gr_mem_cnt; ++cnt)
+	      || resultbuf->gr_passwd[gr_resp.gr_passwd_len - 1] != '\0'
+	      || ({for (cnt = 0; cnt < gr_resp.gr_mem_cnt; ++cnt)
 		     if (resultbuf->gr_mem[cnt][len[cnt] - 1] != '\0')
 		       break;
-	  	   cnt < gr_resp->gr_mem_cnt; }))
+	  	   cnt < gr_resp.gr_mem_cnt; }))
 	    {
 	      /* We cannot use the database.  */
-	      retval = -1;
+	      retval = mapped->head->gc_cycle != gc_cycle ? -2 : -1;
 	      goto out_close;
 	    }
 
@@ -274,19 +296,21 @@ nscd_getgr_r (const char *key, size_t keylen, request_type type,
   if (sock != -1)
     close_not_cancel_no_status (sock);
  out:
-  if (__nscd_drop_map_ref (mapped, &gc_cycle) != 0 && retval != -1)
+  if (__nscd_drop_map_ref (mapped, &gc_cycle) != 0)
     {
       /* When we come here this means there has been a GC cycle while we
 	 were looking for the data.  This means the data might have been
 	 inconsistent.  Retry if possible.  */
-      if ((gc_cycle & 1) != 0)
+      if ((gc_cycle & 1) != 0 || ++nretries == 5 || retval == -1)
 	{
 	  /* nscd is just running gc now.  Disable using the mapping.  */
-	  __nscd_unmap (mapped);
+	  if (atomic_decrement_val (&mapped->counter) == 0)
+	    __nscd_unmap (mapped);
 	  mapped = NO_MAPPING;
 	}
 
-      goto retry;
+      if (retval != -1)
+	goto retry;
     }
 
   return retval;
diff --git a/nscd/nscd_gethst_r.c b/nscd/nscd_gethst_r.c
index e83e4823ea..03b73a4a47 100644
--- a/nscd/nscd_gethst_r.c
+++ b/nscd/nscd_gethst_r.c
@@ -113,7 +113,6 @@ nscd_gethst_r (const char *key, size_t keylen, request_type type,
 			       &gc_cycle);
 
  retry:;
-  const hst_response_header *hst_resp = NULL;
   const char *h_name = NULL;
   const uint32_t *aliases_len = NULL;
   const char *addr_list = NULL;
@@ -121,18 +120,27 @@ nscd_gethst_r (const char *key, size_t keylen, request_type type,
   int retval = -1;
   const char *recend = (const char *) ~UINTMAX_C (0);
   int sock = -1;
+  hst_response_header hst_resp;
   if (mapped != NO_MAPPING)
     {
-      const struct datahead *found = __nscd_cache_search (type, key, keylen,
-							  mapped);
+      /* No const qualifier, as it can change during garbage collection.  */
+      struct datahead *found = __nscd_cache_search (type, key, keylen, mapped);
       if (found != NULL)
 	{
-	  hst_resp = &found->data[0].hstdata;
-	  h_name = (char *) (hst_resp + 1);
-	  aliases_len = (uint32_t *) (h_name + hst_resp->h_name_len);
+	  h_name = (char *) (&found->data[0].hstdata + 1);
+	  hst_resp = found->data[0].hstdata;
+	  aliases_len = (uint32_t *) (h_name + hst_resp.h_name_len);
 	  addr_list = ((char *) aliases_len
-		       + hst_resp->h_aliases_cnt * sizeof (uint32_t));
-	  addr_list_len = hst_resp->h_addr_list_cnt * INADDRSZ;
+		       + hst_resp.h_aliases_cnt * sizeof (uint32_t));
+	  addr_list_len = hst_resp.h_addr_list_cnt * INADDRSZ;
+	  recend = (const char *) found->data + found->recsize;
+	  /* Now check if we can trust hst_resp fields.  If GC is
+	     in progress, it can contain anything.  */
+	  if (mapped->head->gc_cycle != gc_cycle)
+	    {
+	      retval = -2;
+	      goto out;
+	    }
 
 #ifndef _STRING_ARCH_unaligned
 	  /* The aliases_len array in the mapped database might very
@@ -142,51 +150,47 @@ nscd_gethst_r (const char *key, size_t keylen, request_type type,
 	  if (((uintptr_t) aliases_len & (__alignof__ (*aliases_len) - 1))
 	      != 0)
 	    {
-	      uint32_t *tmp = alloca (hst_resp->h_aliases_cnt
+	      uint32_t *tmp = alloca (hst_resp.h_aliases_cnt
 				      * sizeof (uint32_t));
 	      aliases_len = memcpy (tmp, aliases_len,
-				    hst_resp->h_aliases_cnt
+				    hst_resp.h_aliases_cnt
 				    * sizeof (uint32_t));
 	    }
 #endif
 	  if (type != GETHOSTBYADDR && type != GETHOSTBYNAME)
 	    {
-	      if (hst_resp->h_length == INADDRSZ)
+	      if (hst_resp.h_length == INADDRSZ)
 		addr_list += addr_list_len;
-	      addr_list_len = hst_resp->h_addr_list_cnt * IN6ADDRSZ;
+	      addr_list_len = hst_resp.h_addr_list_cnt * IN6ADDRSZ;
 	    }
-	  recend = (const char *) found->data + found->recsize;
 	  if (__builtin_expect ((const char *) addr_list + addr_list_len
 				> recend, 0))
-	    goto out_close;
+	    goto out;
 	}
     }
 
-  hst_response_header hst_resp_mem;
-  if (hst_resp == NULL)
+  if (h_name == NULL)
     {
-      sock = __nscd_open_socket (key, keylen, type, &hst_resp_mem,
-				 sizeof (hst_resp_mem));
+      sock = __nscd_open_socket (key, keylen, type, &hst_resp,
+				 sizeof (hst_resp));
       if (sock == -1)
 	{
 	  __nss_not_use_nscd_hosts = 1;
 	  goto out;
 	}
-
-      hst_resp = &hst_resp_mem;
     }
 
   /* No value found so far.  */
   *result = NULL;
 
-  if (__builtin_expect (hst_resp->found == -1, 0))
+  if (__builtin_expect (hst_resp.found == -1, 0))
     {
       /* The daemon does not cache this database.  */
       __nss_not_use_nscd_hosts = 1;
       goto out_close;
     }
 
-  if (hst_resp->found == 1)
+  if (hst_resp.found == 1)
     {
       char *cp = buffer;
       uintptr_t align1;
@@ -201,15 +205,15 @@ nscd_gethst_r (const char *key, size_t keylen, request_type type,
 	 align the pointer and the base of the h_addr_list pointers.  */
       align1 = ((__alignof__ (char *) - (cp - ((char *) 0)))
 		& (__alignof__ (char *) - 1));
-      align2 = ((__alignof__ (char *) - ((cp + align1 + hst_resp->h_name_len)
+      align2 = ((__alignof__ (char *) - ((cp + align1 + hst_resp.h_name_len)
 					 - ((char *) 0)))
 		& (__alignof__ (char *) - 1));
-      if (buflen < (align1 + hst_resp->h_name_len + align2
-		    + ((hst_resp->h_aliases_cnt + hst_resp->h_addr_list_cnt
+      if (buflen < (align1 + hst_resp.h_name_len + align2
+		    + ((hst_resp.h_aliases_cnt + hst_resp.h_addr_list_cnt
 			+ 2)
 		       * sizeof (char *))
-		    + hst_resp->h_addr_list_cnt * (type == AF_INET
-						   ? INADDRSZ : IN6ADDRSZ)))
+		    + hst_resp.h_addr_list_cnt * (type == AF_INET
+						  ? INADDRSZ : IN6ADDRSZ)))
 	{
 	no_room:
 	  *h_errnop = NETDB_INTERNAL;
@@ -221,12 +225,12 @@ nscd_gethst_r (const char *key, size_t keylen, request_type type,
 
       /* Prepare the result as far as we can.  */
       resultbuf->h_aliases = (char **) cp;
-      cp += (hst_resp->h_aliases_cnt + 1) * sizeof (char *);
+      cp += (hst_resp.h_aliases_cnt + 1) * sizeof (char *);
       resultbuf->h_addr_list = (char **) cp;
-      cp += (hst_resp->h_addr_list_cnt + 1) * sizeof (char *);
+      cp += (hst_resp.h_addr_list_cnt + 1) * sizeof (char *);
 
       resultbuf->h_name = cp;
-      cp += hst_resp->h_name_len + align2;
+      cp += hst_resp.h_name_len + align2;
 
       if (type == GETHOSTBYADDR || type == GETHOSTBYNAME)
 	{
@@ -238,7 +242,7 @@ nscd_gethst_r (const char *key, size_t keylen, request_type type,
 	  resultbuf->h_addrtype = AF_INET6;
 	  resultbuf->h_length = IN6ADDRSZ;
 	}
-      for (cnt = 0; cnt < hst_resp->h_addr_list_cnt; ++cnt)
+      for (cnt = 0; cnt < hst_resp.h_addr_list_cnt; ++cnt)
 	{
 	  resultbuf->h_addr_list[cnt] = cp;
 	  cp += resultbuf->h_length;
@@ -250,47 +254,47 @@ nscd_gethst_r (const char *key, size_t keylen, request_type type,
 	  struct iovec vec[4];
 
 	  vec[0].iov_base = resultbuf->h_name;
-	  vec[0].iov_len = hst_resp->h_name_len;
-	  total_len = hst_resp->h_name_len;
+	  vec[0].iov_len = hst_resp.h_name_len;
+	  total_len = hst_resp.h_name_len;
 	  n = 1;
 
-	  if (hst_resp->h_aliases_cnt > 0)
+	  if (hst_resp.h_aliases_cnt > 0)
 	    {
-	      aliases_len = alloca (hst_resp->h_aliases_cnt
+	      aliases_len = alloca (hst_resp.h_aliases_cnt
 				    * sizeof (uint32_t));
 	      vec[n].iov_base = (void *) aliases_len;
-	      vec[n].iov_len = hst_resp->h_aliases_cnt * sizeof (uint32_t);
+	      vec[n].iov_len = hst_resp.h_aliases_cnt * sizeof (uint32_t);
 
-	      total_len += hst_resp->h_aliases_cnt * sizeof (uint32_t);
+	      total_len += hst_resp.h_aliases_cnt * sizeof (uint32_t);
 	      ++n;
 	    }
 
 	  if (type == GETHOSTBYADDR || type == GETHOSTBYNAME)
 	    {
 	      vec[n].iov_base = resultbuf->h_addr_list[0];
-	      vec[n].iov_len = hst_resp->h_addr_list_cnt * INADDRSZ;
+	      vec[n].iov_len = hst_resp.h_addr_list_cnt * INADDRSZ;
 
-	      total_len += hst_resp->h_addr_list_cnt * INADDRSZ;
+	      total_len += hst_resp.h_addr_list_cnt * INADDRSZ;
 
 	      ++n;
 	    }
 	  else
 	    {
-	      if (hst_resp->h_length == INADDRSZ)
+	      if (hst_resp.h_length == INADDRSZ)
 		{
-		  ignore = alloca (hst_resp->h_addr_list_cnt * INADDRSZ);
+		  ignore = alloca (hst_resp.h_addr_list_cnt * INADDRSZ);
 		  vec[n].iov_base = ignore;
-		  vec[n].iov_len = hst_resp->h_addr_list_cnt * INADDRSZ;
+		  vec[n].iov_len = hst_resp.h_addr_list_cnt * INADDRSZ;
 
-		  total_len += hst_resp->h_addr_list_cnt * INADDRSZ;
+		  total_len += hst_resp.h_addr_list_cnt * INADDRSZ;
 
 		  ++n;
 		}
 
 	      vec[n].iov_base = resultbuf->h_addr_list[0];
-	      vec[n].iov_len = hst_resp->h_addr_list_cnt * IN6ADDRSZ;
+	      vec[n].iov_len = hst_resp.h_addr_list_cnt * IN6ADDRSZ;
 
-	      total_len += hst_resp->h_addr_list_cnt * IN6ADDRSZ;
+	      total_len += hst_resp.h_addr_list_cnt * IN6ADDRSZ;
 
 	      ++n;
 	    }
@@ -300,13 +304,13 @@ nscd_gethst_r (const char *key, size_t keylen, request_type type,
 	}
       else
 	{
-	  memcpy (resultbuf->h_name, h_name, hst_resp->h_name_len);
+	  memcpy (resultbuf->h_name, h_name, hst_resp.h_name_len);
 	  memcpy (resultbuf->h_addr_list[0], addr_list, addr_list_len);
 	}
 
       /*  Now we also can read the aliases.  */
       total_len = 0;
-      for (cnt = 0; cnt < hst_resp->h_aliases_cnt; ++cnt)
+      for (cnt = 0; cnt < hst_resp.h_aliases_cnt; ++cnt)
 	{
 	  resultbuf->h_aliases[cnt] = cp;
 	  cp += aliases_len[cnt];
@@ -316,10 +320,25 @@ nscd_gethst_r (const char *key, size_t keylen, request_type type,
 
       if (__builtin_expect ((const char *) addr_list + addr_list_len
 			    + total_len > recend, 0))
-	goto out_close;
+	{
+	  /* aliases_len array might contain garbage during nscd GC cycle,
+	     retry rather than fail in that case.  */
+	  if (addr_list != NULL && mapped->head->gc_cycle != gc_cycle)
+	    retval = -2;
+	  goto out_close;
+	}
       /* See whether this would exceed the buffer capacity.  */
       if (__builtin_expect (cp > buffer + buflen, 0))
-	goto no_room;
+	{
+	  /* aliases_len array might contain garbage during nscd GC cycle,
+	     retry rather than fail in that case.  */
+	  if (addr_list != NULL && mapped->head->gc_cycle != gc_cycle)
+	    {
+	      retval = -2;
+	      goto out_close;
+	    }
+	  goto no_room;
+	}
 
       /* And finally read the aliases.  */
       if (addr_list == NULL)
@@ -338,14 +357,18 @@ nscd_gethst_r (const char *key, size_t keylen, request_type type,
 		  (const char *) addr_list + addr_list_len, total_len);
 
 	  /* Try to detect corrupt databases.  */
-	  if (resultbuf->h_name[hst_resp->h_name_len - 1] != '\0'
-	      || ({for (cnt = 0; cnt < hst_resp->h_aliases_cnt; ++cnt)
+	  if (resultbuf->h_name[hst_resp.h_name_len - 1] != '\0'
+	      || ({for (cnt = 0; cnt < hst_resp.h_aliases_cnt; ++cnt)
 		     if (resultbuf->h_aliases[cnt][aliases_len[cnt] - 1]
 			 != '\0')
 		       break;
-		   cnt < hst_resp->h_aliases_cnt; }))
-	    /* We cannot use the database.  */
-	    goto out_close;
+		   cnt < hst_resp.h_aliases_cnt; }))
+	    {
+	      /* We cannot use the database.  */
+	      if (mapped->head->gc_cycle != gc_cycle)
+		retval = -2;
+	      goto out_close;
+	    }
 
 	  retval = 0;
 	  *result = resultbuf;
@@ -354,7 +377,7 @@ nscd_gethst_r (const char *key, size_t keylen, request_type type,
   else
     {
       /* Store the error number.  */
-      *h_errnop = hst_resp->error;
+      *h_errnop = hst_resp.error;
 
       /* The `errno' to some value != ERANGE.  */
       __set_errno (ENOENT);
@@ -366,19 +389,21 @@ nscd_gethst_r (const char *key, size_t keylen, request_type type,
   if (sock != -1)
     close_not_cancel_no_status (sock);
  out:
-  if (__nscd_drop_map_ref (mapped, &gc_cycle) != 0 && retval != -1)
+  if (__nscd_drop_map_ref (mapped, &gc_cycle) != 0)
     {
       /* When we come here this means there has been a GC cycle while we
 	 were looking for the data.  This means the data might have been
 	 inconsistent.  Retry if possible.  */
-      if ((gc_cycle & 1) != 0 || ++nretries == 5)
+      if ((gc_cycle & 1) != 0 || ++nretries == 5 || retval == -1)
 	{
 	  /* nscd is just running gc now.  Disable using the mapping.  */
-	  __nscd_unmap (mapped);
+	  if (atomic_decrement_val (&mapped->counter) == 0)
+	    __nscd_unmap (mapped);
 	  mapped = NO_MAPPING;
 	}
 
-      goto retry;
+      if (retval != -1)
+	goto retry;
     }
 
   return retval;
diff --git a/nscd/nscd_getpw_r.c b/nscd/nscd_getpw_r.c
index e8e4d7364f..b84baa1a66 100644
--- a/nscd/nscd_getpw_r.c
+++ b/nscd/nscd_getpw_r.c
@@ -1,4 +1,5 @@
-/* Copyright (C) 1998, 1999, 2003, 2004, 2005 Free Software Foundation, Inc.
+/* Copyright (C) 1998, 1999, 2003, 2004, 2005, 2007
+   Free Software Foundation, Inc.
    This file is part of the GNU C Library.
    Contributed by Thorsten Kukuk <kukuk@uni-paderborn.de>, 1998.
 
@@ -88,76 +89,81 @@ nscd_getpw_r (const char *key, size_t keylen, request_type type,
 	      struct passwd **result)
 {
   int gc_cycle;
+  int nretries = 0;
+
   /* If the mapping is available, try to search there instead of
      communicating with the nscd.  */
   struct mapped_database *mapped;
   mapped = __nscd_get_map_ref (GETFDPW, "passwd", &map_handle, &gc_cycle);
 
  retry:;
-  const pw_response_header *pw_resp = NULL;
   const char *pw_name = NULL;
   int retval = -1;
   const char *recend = (const char *) ~UINTMAX_C (0);
+  pw_response_header pw_resp;
 
   if (mapped != NO_MAPPING)
     {
-      const struct datahead *found = __nscd_cache_search (type, key, keylen,
-							  mapped);
+      struct datahead *found = __nscd_cache_search (type, key, keylen, mapped);
       if (found != NULL)
 	{
-	  pw_resp = &found->data[0].pwdata;
-	  pw_name = (const char *) (pw_resp + 1);
+	  pw_name = (const char *) (&found->data[0].pwdata + 1);
+	  pw_resp = found->data[0].pwdata;
 	  recend = (const char *) found->data + found->recsize;
+	  /* Now check if we can trust pw_resp fields.  If GC is
+	     in progress, it can contain anything.  */
+	  if (mapped->head->gc_cycle != gc_cycle)
+	    {
+	      retval = -2;
+	      goto out;
+	    }
 	}
     }
 
-  pw_response_header pw_resp_mem;
   int sock = -1;
-  if (pw_resp == NULL)
+  if (pw_name == NULL)
     {
-      sock = __nscd_open_socket (key, keylen, type, &pw_resp_mem,
-				 sizeof (pw_resp_mem));
+      sock = __nscd_open_socket (key, keylen, type, &pw_resp,
+				 sizeof (pw_resp));
       if (sock == -1)
 	{
 	  __nss_not_use_nscd_passwd = 1;
 	  goto out;
 	}
-
-      pw_resp = &pw_resp_mem;
     }
 
   /* No value found so far.  */
   *result = NULL;
 
-  if (__builtin_expect (pw_resp->found == -1, 0))
+  if (__builtin_expect (pw_resp.found == -1, 0))
     {
       /* The daemon does not cache this database.  */
       __nss_not_use_nscd_passwd = 1;
       goto out_close;
     }
 
-  if (pw_resp->found == 1)
+  if (pw_resp.found == 1)
     {
       /* Set the information we already have.  */
-      resultbuf->pw_uid = pw_resp->pw_uid;
-      resultbuf->pw_gid = pw_resp->pw_gid;
+      resultbuf->pw_uid = pw_resp.pw_uid;
+      resultbuf->pw_gid = pw_resp.pw_gid;
 
       char *p = buffer;
       /* get pw_name */
       resultbuf->pw_name = p;
-      p += pw_resp->pw_name_len;
+      p += pw_resp.pw_name_len;
       /* get pw_passwd */
       resultbuf->pw_passwd = p;
-      p += pw_resp->pw_passwd_len;
+      p += pw_resp.pw_passwd_len;
       /* get pw_gecos */
       resultbuf->pw_gecos = p;
-      p += pw_resp->pw_gecos_len;
+      p += pw_resp.pw_gecos_len;
       /* get pw_dir */
       resultbuf->pw_dir = p;
-      p += pw_resp->pw_dir_len;
+      p += pw_resp.pw_dir_len;
       /* get pw_pshell */
       resultbuf->pw_shell = p;
-      p += pw_resp->pw_shell_len;
+      p += pw_resp.pw_shell_len;
 
       ssize_t total = p - buffer;
       if (__builtin_expect (pw_name + total > recend, 0))
@@ -189,14 +195,14 @@ nscd_getpw_r (const char *key, size_t keylen, request_type type,
 	  memcpy (resultbuf->pw_name, pw_name, total);
 
 	  /* Try to detect corrupt databases.  */
-	  if (resultbuf->pw_name[pw_resp->pw_name_len - 1] != '\0'
-	      || resultbuf->pw_passwd[pw_resp->pw_passwd_len - 1] != '\0'
-	      || resultbuf->pw_gecos[pw_resp->pw_gecos_len - 1] != '\0'
-	      || resultbuf->pw_dir[pw_resp->pw_dir_len - 1] != '\0'
-	      || resultbuf->pw_shell[pw_resp->pw_shell_len - 1] != '\0')
+	  if (resultbuf->pw_name[pw_resp.pw_name_len - 1] != '\0'
+	      || resultbuf->pw_passwd[pw_resp.pw_passwd_len - 1] != '\0'
+	      || resultbuf->pw_gecos[pw_resp.pw_gecos_len - 1] != '\0'
+	      || resultbuf->pw_dir[pw_resp.pw_dir_len - 1] != '\0'
+	      || resultbuf->pw_shell[pw_resp.pw_shell_len - 1] != '\0')
 	    {
 	      /* We cannot use the database.  */
-	      retval = -1;
+	      retval = mapped->head->gc_cycle != gc_cycle ? -2 : -1;
 	      goto out_close;
 	    }
 
@@ -215,19 +221,21 @@ nscd_getpw_r (const char *key, size_t keylen, request_type type,
   if (sock != -1)
     close_not_cancel_no_status (sock);
  out:
-  if (__nscd_drop_map_ref (mapped, &gc_cycle) != 0 && retval != -1)
+  if (__nscd_drop_map_ref (mapped, &gc_cycle) != 0)
     {
       /* When we come here this means there has been a GC cycle while we
 	 were looking for the data.  This means the data might have been
 	 inconsistent.  Retry if possible.  */
-      if ((gc_cycle & 1) != 0)
+      if ((gc_cycle & 1) != 0 || ++nretries == 5 || retval == -1)
 	{
 	  /* nscd is just running gc now.  Disable using the mapping.  */
-	  __nscd_unmap (mapped);
+	  if (atomic_decrement_val (&mapped->counter) == 0)
+	    __nscd_unmap (mapped);
 	  mapped = NO_MAPPING;
 	}
 
-      goto retry;
+      if (retval != -1)
+	goto retry;
     }
 
   return retval;
diff --git a/nscd/nscd_getserv_r.c b/nscd/nscd_getserv_r.c
index 87d3d31e2c..86242be7ac 100644
--- a/nscd/nscd_getserv_r.c
+++ b/nscd/nscd_getserv_r.c
@@ -93,7 +93,6 @@ nscd_getserv_r (const char *crit, size_t critlen, const char *proto,
 		     "/", 1), proto ?: "", protolen + 1);
 
  retry:;
-  const serv_response_header *serv_resp = NULL;
   const char *s_name = NULL;
   const char *s_proto = NULL;
   const uint32_t *aliases_len = NULL;
@@ -101,19 +100,28 @@ nscd_getserv_r (const char *crit, size_t critlen, const char *proto,
   int retval = -1;
   const char *recend = (const char *) ~UINTMAX_C (0);
   int sock = -1;
+  serv_response_header serv_resp;
+
   if (mapped != NO_MAPPING)
     {
-      const struct datahead *found = __nscd_cache_search (type, key, keylen,
-							  mapped);
+      struct datahead *found = __nscd_cache_search (type, key, keylen, mapped);
 
       if (found != NULL)
 	{
-	  serv_resp = &found->data[0].servdata;
-	  s_name = (char *) (serv_resp + 1);
-	  s_proto = s_name + serv_resp->s_name_len;
-	  aliases_len = (uint32_t *) (s_proto + serv_resp->s_proto_len);
+	  s_name = (char *) (&found->data[0].servdata + 1);
+	  serv_resp = found->data[0].servdata;
+	  s_proto = s_name + serv_resp.s_name_len;
+	  aliases_len = (uint32_t *) (s_proto + serv_resp.s_proto_len);
 	  aliases_list = ((char *) aliases_len
-			  + serv_resp->s_aliases_cnt * sizeof (uint32_t));
+			  + serv_resp.s_aliases_cnt * sizeof (uint32_t));
+	  recend = (const char *) found->data + found->recsize;
+	  /* Now check if we can trust serv_resp fields.  If GC is
+	     in progress, it can contain anything.  */
+	  if (mapped->head->gc_cycle != gc_cycle)
+	    {
+	      retval = -2;
+	      goto out;
+	    }
 
 #ifndef _STRING_ARCH_unaligned
 	  /* The aliases_len array in the mapped database might very
@@ -123,46 +131,42 @@ nscd_getserv_r (const char *crit, size_t critlen, const char *proto,
 	  if (((uintptr_t) aliases_len & (__alignof__ (*aliases_len) - 1))
 	      != 0)
 	    {
-	      uint32_t *tmp = alloca (serv_resp->s_aliases_cnt
+	      uint32_t *tmp = alloca (serv_resp.s_aliases_cnt
 				      * sizeof (uint32_t));
 	      aliases_len = memcpy (tmp, aliases_len,
-				    serv_resp->s_aliases_cnt
+				    serv_resp.s_aliases_cnt
 				    * sizeof (uint32_t));
 	    }
 #endif
-	  recend = (const char *) found->data + found->recsize;
 	  if (__builtin_expect ((const char *) aliases_len
-				+ serv_resp->s_aliases_cnt * sizeof (uint32_t)
+				+ serv_resp.s_aliases_cnt * sizeof (uint32_t)
 				> recend, 0))
-	    goto out_close;
+	    goto out;
 	}
     }
 
-  serv_response_header serv_resp_mem;
-  if (serv_resp == NULL)
+  if (s_name == NULL)
     {
-      sock = __nscd_open_socket (key, keylen, type, &serv_resp_mem,
-				 sizeof (serv_resp_mem));
+      sock = __nscd_open_socket (key, keylen, type, &serv_resp,
+				 sizeof (serv_resp));
       if (sock == -1)
 	{
 	  __nss_not_use_nscd_services = 1;
 	  goto out;
 	}
-
-      serv_resp = &serv_resp_mem;
     }
 
   /* No value found so far.  */
   *result = NULL;
 
-  if (__builtin_expect (serv_resp->found == -1, 0))
+  if (__builtin_expect (serv_resp.found == -1, 0))
     {
       /* The daemon does not cache this database.  */
       __nss_not_use_nscd_services = 1;
       goto out_close;
     }
 
-  if (serv_resp->found == 1)
+  if (serv_resp.found == 1)
     {
       char *cp = buf;
       uintptr_t align1;
@@ -176,13 +180,13 @@ nscd_getserv_r (const char *crit, size_t critlen, const char *proto,
 	 align the pointer and the base of the h_addr_list pointers.  */
       align1 = ((__alignof__ (char *) - (cp - ((char *) 0)))
 		& (__alignof__ (char *) - 1));
-      align2 = ((__alignof__ (char *) - ((cp + align1 + serv_resp->s_name_len
-					  + serv_resp->s_proto_len)
+      align2 = ((__alignof__ (char *) - ((cp + align1 + serv_resp.s_name_len
+					  + serv_resp.s_proto_len)
 					 - ((char *) 0)))
 		& (__alignof__ (char *) - 1));
-      if (buflen < (align1 + serv_resp->s_name_len + serv_resp->s_proto_len
+      if (buflen < (align1 + serv_resp.s_name_len + serv_resp.s_proto_len
 		    + align2
-		    + (serv_resp->s_aliases_cnt + 1) * sizeof (char *)))
+		    + (serv_resp.s_aliases_cnt + 1) * sizeof (char *)))
 	{
 	no_room:
 	  __set_errno (ERANGE);
@@ -193,31 +197,31 @@ nscd_getserv_r (const char *crit, size_t critlen, const char *proto,
 
       /* Prepare the result as far as we can.  */
       resultbuf->s_aliases = (char **) cp;
-      cp += (serv_resp->s_aliases_cnt + 1) * sizeof (char *);
+      cp += (serv_resp.s_aliases_cnt + 1) * sizeof (char *);
 
       resultbuf->s_name = cp;
-      cp += serv_resp->s_name_len;
+      cp += serv_resp.s_name_len;
       resultbuf->s_proto = cp;
-      cp += serv_resp->s_proto_len + align2;
-      resultbuf->s_port = serv_resp->s_port;
+      cp += serv_resp.s_proto_len + align2;
+      resultbuf->s_port = serv_resp.s_port;
 
       if (s_name == NULL)
 	{
 	  struct iovec vec[2];
 
 	  vec[0].iov_base = resultbuf->s_name;
-	  vec[0].iov_len = serv_resp->s_name_len + serv_resp->s_proto_len;
+	  vec[0].iov_len = serv_resp.s_name_len + serv_resp.s_proto_len;
 	  total_len = vec[0].iov_len;
 	  n = 1;
 
-	  if (serv_resp->s_aliases_cnt > 0)
+	  if (serv_resp.s_aliases_cnt > 0)
 	    {
-	      aliases_len = alloca (serv_resp->s_aliases_cnt
+	      aliases_len = alloca (serv_resp.s_aliases_cnt
 				    * sizeof (uint32_t));
 	      vec[n].iov_base = (void *) aliases_len;
-	      vec[n].iov_len = serv_resp->s_aliases_cnt * sizeof (uint32_t);
+	      vec[n].iov_len = serv_resp.s_aliases_cnt * sizeof (uint32_t);
 
-	      total_len += serv_resp->s_aliases_cnt * sizeof (uint32_t);
+	      total_len += serv_resp.s_aliases_cnt * sizeof (uint32_t);
 	      ++n;
 	    }
 
@@ -226,11 +230,11 @@ nscd_getserv_r (const char *crit, size_t critlen, const char *proto,
 	}
       else
 	memcpy (resultbuf->s_name, s_name,
-		serv_resp->s_name_len + serv_resp->s_proto_len);
+		serv_resp.s_name_len + serv_resp.s_proto_len);
 
       /*  Now we also can read the aliases.  */
       total_len = 0;
-      for (cnt = 0; cnt < serv_resp->s_aliases_cnt; ++cnt)
+      for (cnt = 0; cnt < serv_resp.s_aliases_cnt; ++cnt)
 	{
 	  resultbuf->s_aliases[cnt] = cp;
 	  cp += aliases_len[cnt];
@@ -240,10 +244,26 @@ nscd_getserv_r (const char *crit, size_t critlen, const char *proto,
 
       if (__builtin_expect ((const char *) aliases_list + total_len > recend,
 			    0))
-	goto out_close;
+	{
+	  /* aliases_len array might contain garbage during nscd GC cycle,
+	     retry rather than fail in that case.  */
+	  if (aliases_list != NULL && mapped->head->gc_cycle != gc_cycle)
+	    retval = -2;
+	  goto out_close;
+	}
+
       /* See whether this would exceed the buffer capacity.  */
       if (__builtin_expect (cp > buf + buflen, 0))
-	goto no_room;
+	{
+	  /* aliases_len array might contain garbage during nscd GC cycle,
+	     retry rather than fail in that case.  */
+	  if (aliases_list != NULL && mapped->head->gc_cycle != gc_cycle)
+	    {
+	      retval = -2;
+	      goto out_close;
+	    }
+	  goto no_room;
+	}
 
       /* And finally read the aliases.  */
       if (aliases_list == NULL)
@@ -261,15 +281,19 @@ nscd_getserv_r (const char *crit, size_t critlen, const char *proto,
 	  memcpy (resultbuf->s_aliases[0], aliases_list, total_len);
 
 	  /* Try to detect corrupt databases.  */
-	  if (resultbuf->s_name[serv_resp->s_name_len - 1] != '\0'
-	      || resultbuf->s_proto[serv_resp->s_proto_len - 1] != '\0'
-	      || ({for (cnt = 0; cnt < serv_resp->s_aliases_cnt; ++cnt)
+	  if (resultbuf->s_name[serv_resp.s_name_len - 1] != '\0'
+	      || resultbuf->s_proto[serv_resp.s_proto_len - 1] != '\0'
+	      || ({for (cnt = 0; cnt < serv_resp.s_aliases_cnt; ++cnt)
 		     if (resultbuf->s_aliases[cnt][aliases_len[cnt] - 1]
 			 != '\0')
 		       break;
-		   cnt < serv_resp->s_aliases_cnt; }))
-	    /* We cannot use the database.  */
-	    goto out_close;
+		   cnt < serv_resp.s_aliases_cnt; }))
+	    {
+	      /* We cannot use the database.  */
+	      if (mapped->head->gc_cycle != gc_cycle)
+		retval = -2;
+	      goto out_close;
+	    }
 
 	  retval = 0;
 	  *result = resultbuf;
@@ -287,19 +311,21 @@ nscd_getserv_r (const char *crit, size_t critlen, const char *proto,
   if (sock != -1)
     close_not_cancel_no_status (sock);
  out:
-  if (__nscd_drop_map_ref (mapped, &gc_cycle) != 0 && retval != -1)
+  if (__nscd_drop_map_ref (mapped, &gc_cycle) != 0)
     {
       /* When we come here this means there has been a GC cycle while we
 	 were looking for the data.  This means the data might have been
 	 inconsistent.  Retry if possible.  */
-      if ((gc_cycle & 1) != 0 || ++nretries == 5)
+      if ((gc_cycle & 1) != 0 || ++nretries == 5 || retval == -1)
 	{
 	  /* nscd is just running gc now.  Disable using the mapping.  */
-	  __nscd_unmap (mapped);
+	  if (atomic_decrement_val (&mapped->counter) == 0)
+	    __nscd_unmap (mapped);
 	  mapped = NO_MAPPING;
 	}
 
-      goto retry;
+      if (retval != -1)
+	goto retry;
     }
 
   return retval;
diff --git a/nscd/nscd_helper.c b/nscd/nscd_helper.c
index 7c45981586..336adfee89 100644
--- a/nscd/nscd_helper.c
+++ b/nscd/nscd_helper.c
@@ -1,4 +1,5 @@
-/* Copyright (C) 1998-2002,2003,2004,2005,2006 Free Software Foundation, Inc.
+/* Copyright (C) 1998-2002,2003,2004,2005,2006,2007
+   Free Software Foundation, Inc.
    This file is part of the GNU C Library.
    Contributed by Ulrich Drepper <drepper@cygnus.com>, 1998.
 
@@ -21,6 +22,7 @@
 #include <errno.h>
 #include <fcntl.h>
 #include <stdbool.h>
+#include <string.h>
 #include <time.h>
 #include <unistd.h>
 #include <sys/mman.h>
@@ -362,7 +364,10 @@ __nscd_get_map_ref (request_type type, const char *name,
 }
 
 
-const struct datahead *
+/* Don't return const struct datahead *, as eventhough the record
+   is normally constant, it can change arbitrarily during nscd
+   garbage collection.  */
+struct datahead *
 __nscd_cache_search (request_type type, const char *key, size_t keylen,
 		     const struct mapped_database *mapped)
 {
@@ -374,16 +379,32 @@ __nscd_cache_search (request_type type, const char *key, size_t keylen,
     {
       struct hashentry *here = (struct hashentry *) (mapped->data + work);
 
+#ifndef _STRING_ARCH_unaligned
+      /* Although during garbage collection when moving struct hashentry
+	 records around we first copy from old to new location and then
+	 adjust pointer from previous hashentry to it, there is no barrier
+	 between those memory writes.  It is very unlikely to hit it,
+	 so check alignment only if a misaligned load can crash the
+	 application.  */
+      if ((uintptr_t) here & (__alignof__ (*here) - 1))
+	return NULL;
+#endif
+
       if (type == here->type
 	  && keylen == here->len
-	  && here->key + here->len <= datasize
+	  && here->key + keylen <= datasize
 	  && memcmp (key, mapped->data + here->key, keylen) == 0
 	  && here->packet + sizeof (struct datahead) <= datasize)
 	{
 	  /* We found the entry.  Increment the appropriate counter.  */
-	  const struct datahead *dh
+	  struct datahead *dh
 	    = (struct datahead *) (mapped->data + here->packet);
 
+#ifndef _STRING_ARCH_unaligned
+	  if ((uintptr_t) dh & (__alignof__ (*dh) - 1))
+	    return NULL;
+#endif
+
 	  /* See whether we must ignore the entry or whether something
 	     is wrong because garbage collection is in progress.  */
 	  if (dh->usable && here->packet + dh->allocsize <= datasize)
diff --git a/nscd/nscd_initgroups.c b/nscd/nscd_initgroups.c
index 97a037d4a9..866455a96c 100644
--- a/nscd/nscd_initgroups.c
+++ b/nscd/nscd_initgroups.c
@@ -1,4 +1,4 @@
-/* Copyright (C) 2004, 2005, 2006 Free Software Foundation, Inc.
+/* Copyright (C) 2004, 2005, 2006, 2007 Free Software Foundation, Inc.
    This file is part of the GNU C Library.
    Contributed by Ulrich Drepper <drepper@redhat.com>, 2004.
 
@@ -39,6 +39,7 @@ __nscd_getgrouplist (const char *user, gid_t group, long int *size,
 {
   size_t userlen = strlen (user) + 1;
   int gc_cycle;
+  int nretries = 0;
 
   /* If the mapping is available, try to search there instead of
      communicating with the nscd.  */
@@ -46,44 +47,49 @@ __nscd_getgrouplist (const char *user, gid_t group, long int *size,
   mapped = __nscd_get_map_ref (GETFDGR, "group", &__gr_map_handle, &gc_cycle);
 
  retry:;
-  const initgr_response_header *initgr_resp = NULL;
   char *respdata = NULL;
   int retval = -1;
   int sock = -1;
+  initgr_response_header initgr_resp;
 
   if (mapped != NO_MAPPING)
     {
-      const struct datahead *found = __nscd_cache_search (INITGROUPS, user,
-							  userlen, mapped);
+      struct datahead *found = __nscd_cache_search (INITGROUPS, user,
+						    userlen, mapped);
       if (found != NULL)
 	{
-	  initgr_resp = &found->data[0].initgrdata;
-	  respdata = (char *) (initgr_resp + 1);
+	  respdata = (char *) (&found->data[0].initgrdata + 1);
+	  initgr_resp = found->data[0].initgrdata;
 	  char *recend = (char *) found->data + found->recsize;
 
-	  if (respdata + initgr_resp->ngrps * sizeof (int32_t) > recend)
+	  /* Now check if we can trust initgr_resp fields.  If GC is
+	     in progress, it can contain anything.  */
+	  if (mapped->head->gc_cycle != gc_cycle)
+	    {
+	      retval = -2;
+	      goto out;
+	    }
+
+	  if (respdata + initgr_resp.ngrps * sizeof (int32_t) > recend)
 	    goto out;
 	}
     }
 
   /* If we do not have the cache mapped, try to get the data over the
      socket.  */
-  initgr_response_header initgr_resp_mem;
-  if (initgr_resp == NULL)
+  if (respdata == NULL)
     {
-      sock = __nscd_open_socket (user, userlen, INITGROUPS, &initgr_resp_mem,
-				 sizeof (initgr_resp_mem));
+      sock = __nscd_open_socket (user, userlen, INITGROUPS, &initgr_resp,
+				 sizeof (initgr_resp));
       if (sock == -1)
 	{
 	  /* nscd not running or wrong version.  */
 	  __nss_not_use_nscd_group = 1;
 	  goto out;
 	}
-
-      initgr_resp = &initgr_resp_mem;
     }
 
-  if (initgr_resp->found == 1)
+  if (initgr_resp.found == 1)
     {
       /* The following code assumes that gid_t and int32_t are the
 	 same size.  This is the case for al existing implementation.
@@ -91,40 +97,40 @@ __nscd_getgrouplist (const char *user, gid_t group, long int *size,
 	 doesn't use memcpy but instead copies each array element one
 	 by one.  */
       assert (sizeof (int32_t) == sizeof (gid_t));
-      assert (initgr_resp->ngrps >= 0);
+      assert (initgr_resp.ngrps >= 0);
 
       /* Make sure we have enough room.  We always count GROUP in even
 	 though we might not end up adding it.  */
-      if (*size < initgr_resp->ngrps + 1)
+      if (*size < initgr_resp.ngrps + 1)
 	{
 	  gid_t *newp = realloc (*groupsp,
-				 (initgr_resp->ngrps + 1) * sizeof (gid_t));
+				 (initgr_resp.ngrps + 1) * sizeof (gid_t));
 	  if (newp == NULL)
 	    /* We cannot increase the buffer size.  */
 	    goto out_close;
 
 	  *groupsp = newp;
-	  *size = initgr_resp->ngrps + 1;
+	  *size = initgr_resp.ngrps + 1;
 	}
 
       if (respdata == NULL)
 	{
 	  /* Read the data from the socket.  */
-	  if ((size_t) __readall (sock, *groupsp, initgr_resp->ngrps
+	  if ((size_t) __readall (sock, *groupsp, initgr_resp.ngrps
 						  * sizeof (gid_t))
-	      == initgr_resp->ngrps * sizeof (gid_t))
-	    retval = initgr_resp->ngrps;
+	      == initgr_resp.ngrps * sizeof (gid_t))
+	    retval = initgr_resp.ngrps;
 	}
       else
 	{
 	  /* Just copy the data.  */
-	  retval = initgr_resp->ngrps;
+	  retval = initgr_resp.ngrps;
 	  memcpy (*groupsp, respdata, retval * sizeof (gid_t));
 	}
     }
   else
     {
-      if (__builtin_expect (initgr_resp->found == -1, 0))
+      if (__builtin_expect (initgr_resp.found == -1, 0))
 	{
 	  /* The daemon does not cache this database.  */
 	  __nss_not_use_nscd_group = 1;
@@ -153,19 +159,21 @@ __nscd_getgrouplist (const char *user, gid_t group, long int *size,
   if (sock != -1)
     close_not_cancel_no_status (sock);
  out:
-  if (__nscd_drop_map_ref (mapped, &gc_cycle) != 0 && retval != -1)
+  if (__nscd_drop_map_ref (mapped, &gc_cycle) != 0)
     {
       /* When we come here this means there has been a GC cycle while we
 	 were looking for the data.  This means the data might have been
 	 inconsistent.  Retry if possible.  */
-      if ((gc_cycle & 1) != 0)
+      if ((gc_cycle & 1) != 0 || ++nretries == 5 || retval == -1)
 	{
 	  /* nscd is just running gc now.  Disable using the mapping.  */
-	  __nscd_unmap (mapped);
+	  if (atomic_decrement_val (&mapped->counter) == 0)
+	    __nscd_unmap (mapped);
 	  mapped = NO_MAPPING;
 	}
 
-      goto retry;
+      if (retval != -1)
+	goto retry;
     }
 
   return retval;