Messages in this thread Patch in this message | | | Date | Tue, 22 Nov 2011 16:23:56 -0800 | From | Greg KH <> | Subject | [49/53] xfs: Fix possible memory corruption in xfs_readlink |
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3.0-stable review patch. If anyone has any objections, please let me know.
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From: Carlos Maiolino <cmaiolino@redhat.com>
commit b52a360b2aa1c59ba9970fb0f52bbb093fcc7a24 upstream.
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> Signed-off-by: Carlos Maiolino <cmaiolino@redhat.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de> --- fs/xfs/xfs_vnodeops.c | 14 ++++++++++---- 1 file changed, 10 insertions(+), 4 deletions(-)
--- a/fs/xfs/xfs_vnodeops.c +++ b/fs/xfs/xfs_vnodeops.c @@ -535,7 +535,7 @@ xfs_readlink( char *link) { xfs_mount_t *mp = ip->i_mount; - int pathlen; + xfs_fsize_t pathlen; int error = 0; trace_xfs_readlink(ip); @@ -545,13 +545,19 @@ xfs_readlink( xfs_ilock(ip, XFS_ILOCK_SHARED); - ASSERT((ip->i_d.di_mode & S_IFMT) == S_IFLNK); - 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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