* sysdeps/unix/fdopendir.c (fdopendir): Make sure descriptor

	allows reading.

1 files changed, 10 insertions, 0 deletions

diff --git a/sysdeps/unix/fdopendir.c b/sysdeps/unix/fdopendir.c
index ef6c97c308..23d08fd7fd 100644
--- a/sysdeps/unix/fdopendir.c
+++ b/sysdeps/unix/fdopendir.c
@@ -18,6 +18,7 @@
 
 #include <dirent.h>
 #include <errno.h>
+#include <fcntl.h>
 #include <sys/stat.h>
 
 #include <not-cancel.h>
@@ -35,6 +36,15 @@ fdopendir (int fd)
       __set_errno (ENOTDIR);
       return NULL;
     }
+  /* Make sure the descriptor allows for reading.  */
+  int flags = __fcntl (fd, F_GETFL);
+  if (__builtin_expect (flags == -1, 0))
+    return NULL;
+  if (__builtin_expect ((flags & O_ACCMODE) == O_WRONLY, 0))
+    {
+      __set_errno (EINVAL);
+      return NULL;
+    }
 
   return __alloc_dir (fd, false, &statbuf);
 }