From: Alex Elder <aelder@sgi.com>
To: XFS Mailing List <xfs@oss.sgi.com>
Cc: Ben Hutchings <ben@decadent.org.uk>,
Carlos Maiolino <cmaiolino@redhat.com>
Subject: [PATCH, updated] xfs: Fix possible memory corruption in xfs_readlink
Date: Mon, 7 Nov 2011 10:10:24 -0600 [thread overview]
Message-ID: <1320682224.3186.5.camel@doink> (raw)
In-Reply-To: <1320156842.30281.28.camel@deadeye>
From: Carlos Maiolino <cmaiolino@redhat.com>
Fixes a possible memory corruption when the link is larger than
MAXPATHLEN and XFS_DEBUG is not enabled. This also remove the
S_ISLNK assert, since the inode mode is checked previously in
xfs_readlink_by_handle() and via VFS.
Updated to address concerns raised by Ben Hutchings about the loose
attention paid to 32- vs 64-bit values, and the lack of handling a
potentially negative pathlen value:
- Changed type of "pathlen" to be xfs_fsize_t, to match that of
ip->i_d.di_size
- Added checking for a negative pathlen to the too-long pathlen
test, and generalized the message that gets reported in that case
to reflect the change
As a result, if a negative pathlen were encountered, this function
would return EFSCORRUPTED (and would fail an assertion for a debug
build)--just as would a too-long pathlen.
Signed-off-by Alex Elder <aelder@sgi.com>
---
fs/xfs/xfs_vnodeops.c | 14 ++++++++++----
1 file changed, 10 insertions(+), 4 deletions(-)
Index: b/fs/xfs/xfs_vnodeops.c
===================================================================
--- a/fs/xfs/xfs_vnodeops.c
+++ b/fs/xfs/xfs_vnodeops.c
@@ -112,7 +112,7 @@ xfs_readlink(
char *link)
{
xfs_mount_t *mp = ip->i_mount;
- int pathlen;
+ xfs_fsize_t pathlen;
int error = 0;
trace_xfs_readlink(ip);
@@ -122,13 +122,19 @@ xfs_readlink(
xfs_ilock(ip, XFS_ILOCK_SHARED);
- ASSERT(S_ISLNK(ip->i_d.di_mode));
- ASSERT(ip->i_d.di_size <= MAXPATHLEN);
-
pathlen = ip->i_d.di_size;
if (!pathlen)
goto out;
+ if (pathlen < 0 || pathlen > MAXPATHLEN) {
+ xfs_alert(mp, "%s: inode (%llu) bad symlink length (%lld)",
+ __func__, (unsigned long long) ip->i_ino,
+ (long long) pathlen);
+ ASSERT(0);
+ return XFS_ERROR(EFSCORRUPTED);
+ }
+
+
if (ip->i_df.if_flags & XFS_IFINLINE) {
memcpy(link, ip->i_df.if_u1.if_data, pathlen);
link[pathlen] = '\0';
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next prev parent reply other threads:[~2011-11-07 16:10 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-11-01 14:14 [PATCH] Fix possible memory corruption in xfs_readlink Ben Hutchings
2011-11-02 17:52 ` Alex Elder
2011-11-02 19:45 ` Christoph Hellwig
2011-11-02 20:22 ` Alex Elder
2011-11-07 16:10 ` Alex Elder [this message]
2011-11-07 16:31 ` [PATCH, updated] xfs: " Carlos Maiolino
2011-11-08 14:38 ` Christoph Hellwig
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