ACK, below my signoff
On Mon, Nov 07, 2011 at 10:10:24AM -0600, Alex Elder wrote:
> From: Carlos Maiolino <cmaiolino@xxxxxxxxxx>
>
> 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@xxxxxxx>
Signed-off-by: Carlos Maiolino <cmaiolino@xxxxxxxxxx>
>
> ---
> 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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--
--Carlos
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