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[PATCH] Fix readdir_r with long file names
- From: Florian Weimer <fweimer at redhat dot com>
- To: libc-alpha <libc-alpha at sourceware dot org>
- Date: Tue, 14 May 2013 13:32:23 +0200
- Subject: [PATCH] Fix readdir_r with long file names
This patch changes readdir_r to return ENAMETOOLONG if the kernel
returns a file name longer than NAME_MAX characters, after the end of
the directory has been reached (so that the directory contents is not
truncated). It also makes the padding compensation code
architecture-agnostic and enables it everywhere.
I have tested this on ppc-redhat-linux (which didn't have the padding
compensation code) and ppc64-redhat-linux (which did). Adding a test
case is difficult because typical file systems enforce the NAME_MAX limit.
--
Florian Weimer / Red Hat Product Security Team
2013-05-14 Florian Weimer <fweimer@redhat.com>
[BZ #14699]
* sysdeps/posix/dirstream.h (struct __dirstream): Add errcode
member.
* sysdeps/posix/opendir.c (__alloc_dir): Initialize errcode
member.
* sysdeps/posix/readdir_r.c (__READDIR_R): Enforce NAME_MAX limit.
Return delayed error code. Remove GETDENTS_64BIT_ALIGNED
conditional.
* sysdeps/unix/sysv/linux/wordsize-64/readdir_r.c: Do not define
GETDENTS_64BIT_ALIGNED.
* sysdeps/unix/sysv/linux/i386/readdir64_r.c: Likewise.
diff --git a/sysdeps/posix/dirstream.h b/sysdeps/posix/dirstream.h
index a7a074d..8e8570d 100644
--- a/sysdeps/posix/dirstream.h
+++ b/sysdeps/posix/dirstream.h
@@ -39,6 +39,8 @@ struct __dirstream
off_t filepos; /* Position of next entry to read. */
+ int errcode; /* Delayed error code. */
+
/* Directory block. */
char data[0] __attribute__ ((aligned (__alignof__ (void*))));
};
diff --git a/sysdeps/posix/opendir.c b/sysdeps/posix/opendir.c
index ddfc3a7..fc05b0f 100644
--- a/sysdeps/posix/opendir.c
+++ b/sysdeps/posix/opendir.c
@@ -231,6 +231,7 @@ __alloc_dir (int fd, bool close_fd, int flags, const struct stat64 *statp)
dirp->size = 0;
dirp->offset = 0;
dirp->filepos = 0;
+ dirp->errcode = 0;
return dirp;
}
diff --git a/sysdeps/posix/readdir_r.c b/sysdeps/posix/readdir_r.c
index b5a8e2e..25db350 100644
--- a/sysdeps/posix/readdir_r.c
+++ b/sysdeps/posix/readdir_r.c
@@ -40,6 +40,7 @@ __READDIR_R (DIR *dirp, DIRENT_TYPE *entry, DIRENT_TYPE **result)
DIRENT_TYPE *dp;
size_t reclen;
const int saved_errno = errno;
+ int ret;
__libc_lock_lock (dirp->lock);
@@ -70,10 +71,10 @@ __READDIR_R (DIR *dirp, DIRENT_TYPE *entry, DIRENT_TYPE **result)
bytes = 0;
__set_errno (saved_errno);
}
+ if (bytes < 0)
+ dirp->errcode = errno;
dp = NULL;
- /* Reclen != 0 signals that an error occurred. */
- reclen = bytes != 0;
break;
}
dirp->size = (size_t) bytes;
@@ -106,29 +107,47 @@ __READDIR_R (DIR *dirp, DIRENT_TYPE *entry, DIRENT_TYPE **result)
dirp->filepos += reclen;
#endif
- /* Skip deleted files. */
+#ifdef NAME_MAX
+ if (reclen > offsetof (DIRENT_TYPE, d_name) + NAME_MAX + 1)
+ {
+ /* The record is very long. It could still fit into the
+ caller-supplied buffer if we can skip padding at the
+ end. */
+ size_t namelen = strlen(dp->d_name);
+ if (namelen <= NAME_MAX)
+ reclen = offsetof (DIRENT_TYPE, d_name) + namelen + 1;
+ else
+ {
+ /* The name is too long. Ignore this file. */
+ dirp->errcode = ENAMETOOLONG;
+ dp->d_ino = 0;
+ continue;
+ }
+ }
+#endif
+
+ /* Skip deleted and ignored files. */
}
while (dp->d_ino == 0);
if (dp != NULL)
{
-#ifdef GETDENTS_64BIT_ALIGNED
- /* The d_reclen value might include padding which is not part of
- the DIRENT_TYPE data structure. */
- reclen = MIN (reclen,
- offsetof (DIRENT_TYPE, d_name) + sizeof (dp->d_name));
-#endif
*result = memcpy (entry, dp, reclen);
-#ifdef GETDENTS_64BIT_ALIGNED
+#ifdef _DIRENT_HAVE_D_RECLEN
entry->d_reclen = reclen;
#endif
}
else
*result = NULL;
+ if (dp != 0)
+ ret = 0;
+ else
+ ret = dirp->errcode;
+
__libc_lock_unlock (dirp->lock);
- return dp != NULL ? 0 : reclen ? errno : 0;
+ return ret;
}
#ifdef __READDIR_R_ALIAS
diff --git a/sysdeps/unix/sysv/linux/i386/readdir64_r.c b/sysdeps/unix/sysv/linux/i386/readdir64_r.c
index 8ebbcfd..a7d114e 100644
--- a/sysdeps/unix/sysv/linux/i386/readdir64_r.c
+++ b/sysdeps/unix/sysv/linux/i386/readdir64_r.c
@@ -18,7 +18,6 @@
#define __READDIR_R __readdir64_r
#define __GETDENTS __getdents64
#define DIRENT_TYPE struct dirent64
-#define GETDENTS_64BIT_ALIGNED 1
#include <sysdeps/posix/readdir_r.c>
diff --git a/sysdeps/unix/sysv/linux/wordsize-64/readdir_r.c b/sysdeps/unix/sysv/linux/wordsize-64/readdir_r.c
index 5ed8e95..290f2c8 100644
--- a/sysdeps/unix/sysv/linux/wordsize-64/readdir_r.c
+++ b/sysdeps/unix/sysv/linux/wordsize-64/readdir_r.c
@@ -1,5 +1,4 @@
#define readdir64_r __no_readdir64_r_decl
-#define GETDENTS_64BIT_ALIGNED 1
#include <sysdeps/posix/readdir_r.c>
#undef readdir64_r
weak_alias (__readdir_r, readdir64_r)