Re: [PATCH] xfs: growfs overruns AGFL buffer on V4 filesystems

Ben Myers
2013-12-05T22:20:22Z

On Thu, Nov 21, 2013 at 03:41:06PM +1100, Dave Chinner wrote:
> From: Dave Chinner <dchinner@redhat.com>
>
> This loop in xfs_growfs_data_private() is incorrect for V4
> superblocks filesystems:
>
> for (bucket = 0; bucket < XFS_AGFL_SIZE(mp); bucket++)
> agfl->agfl_bno[bucket] = cpu_to_be32(NULLAGBLOCK);
>
> For V4 filesystems, we don't have a agfl header structure, and so
> XFS_AGFL_SIZE() returns an entire sector's worth of entries, which
> we then index from an offset into the sector. Hence: buffer overrun.
>
> This problem was introduced in 3.10 by commit 77c95bba ("xfs: add
> CRC checks to the AGFL") which changed the AGFL structure but failed
> to update the growfs code to handle the different structures.
>
> Fix it by using the correct offset into the buffer for both V4 and
> V5 filesystems.
>
> Cc: <stable@vger.kernel.org>
> Signed-off-by: Dave Chinner <dchinner@redhat.com>

Applied this one. I'll add it to an upcoming 3.13 pull request as well.

Thanks,
Ben