diff options
Diffstat (limited to 'nscd/nscd_helper.c')
| -rw-r--r-- | nscd/nscd_helper.c | 29 |
1 files changed, 25 insertions, 4 deletions
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) |