Commit f94c4457 authored Nov 21, 2013 by Dave Chinner Committed by Ben Myers Dec 10, 2013

xfs: growfs overruns AGFL buffer on V4 filesystems



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>
Reviewed-by: Jie Liu <jeff.liu@oracle.com>
Signed-off-by: Ben Myers <bpm@sgi.com>

(cherry picked from commit b7d961b3)

parent 2f42d612

fs/xfs/xfs_fsops.c

+5 −1

Original line number	Diff line number	Diff line
		@@ -220,6 +220,8 @@ xfs_growfs_data_private(
		*/
		nfree = 0;
		for (agno = nagcount - 1; agno >= oagcount; agno--, new -= agsize) {
		__be32 *agfl_bno;

		/*
		* AG freespace header block
		*/
		@@ -279,8 +281,10 @@ xfs_growfs_data_private(
		agfl->agfl_seqno = cpu_to_be32(agno);
		uuid_copy(&agfl->agfl_uuid, &mp->m_sb.sb_uuid);
		}

		agfl_bno = XFS_BUF_TO_AGFL_BNO(mp, bp);
		for (bucket = 0; bucket < XFS_AGFL_SIZE(mp); bucket++)
		agfl->agfl_bno[bucket] = cpu_to_be32(NULLAGBLOCK);
		agfl_bno[bucket] = cpu_to_be32(NULLAGBLOCK);

		error = xfs_bwrite(bp);
		xfs_buf_relse(bp);

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