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SubjectRe: [v2.6.34-stable 013/165] xfs: Fix possible memory corruption in xfs_readlink
On 12-08-17 11:38 AM, Herton Ronaldo Krzesinski wrote:
> On Wed, Aug 15, 2012 at 03:45:57PM -0400, Paul Gortmaker wrote:
>> From: Carlos Maiolino <cmaiolino@redhat.com>
>>
>> -------------------
>> This is a commit scheduled for the next v2.6.34 longterm release.
>> http://git.kernel.org/?p=linux/kernel/git/paulg/longterm-queue-2.6.34.git
>> If you see a problem with using this for longterm, please comment.
>> -------------------
>>
>> 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>
>> [PG: no xfs_alert in 2.6.34; use xfs_fs_cmn_err(CE_ALERT, ...) instead]
>> Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
> [...]
>
> commit 9b025eb3a89e041bab6698e3858706be2385d692 ("xfs: Fix missing
> xfs_iunlock() on error recovery path in xfs_readlink()") addresses a
> regression with this change, something to consider for inclusion too.

Thanks again Herton. You've convinced me that I need to write
a script that looks for the cherry picked commit ID prefix being
mentioned anywhere in the changelog of any and all new commits
beyond it. It would be a good sanity check...

P.

>


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