From: Carlos Maiolino Date: Mon, 7 Nov 2011 16:10:24 +0000 (+0000) Subject: xfs: Fix possible memory corruption in xfs_readlink X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=b52a360b;p=linux-beck.git xfs: Fix possible memory corruption in xfs_readlink 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 Signed-off-by: Carlos Maiolino Reviewed-by: Christoph Hellwig --- diff --git a/fs/xfs/xfs_vnodeops.c b/fs/xfs/xfs_vnodeops.c index 4ecf2a549060..ce9268a2f56b 100644 --- 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';