From: Eric Sandeen <sandeen@sandeen.net>
To: xfs-oss <xfs@oss.sgi.com>, Jesse Stroik <jstroik@ssec.wisc.edu>
Subject: [PATCH] xfs_repair: fix verify_ag_bno() overflow
Date: Wed, 01 Jul 2009 15:33:03 -0500 [thread overview]
Message-ID: <4A4BC7FF.6050004@sandeen.net> (raw)
The last test in verify_ag_bno() may overflow:
return (agbno >= (sbp->sb_dblocks -
((sbp->sb_agcount - 1) * sbp->sb_agblocks)));
because sb_agcount & sb_agblocks are 32-bit integers; this
may then miss corrupt agbnos for the last ag, which can in
turn lead to out of bounds memory accesses later, for example
when the block nr is used to offset in set_agbno_state():
addr = ba_bmap[(agno)] + (ag_blockno)/XR_BB_NUM;
Also make the first test simpler; agbno > sb_agblocks
is -always- bad, regardless of the agno. This may even
speed it up a tiny bit.
Reported-by: Jesse Stroik <jstroik@ssec.wisc.edu>
Signed-off-by: Eric Sandeen <sandeen@sandeen.net>
---
diff --git a/repair/dinode.c b/repair/dinode.c
index fdf52db..f50f1ad 100644
--- a/repair/dinode.c
+++ b/repair/dinode.c
@@ -315,11 +315,14 @@ verify_ag_bno(xfs_sb_t *sbp,
xfs_agnumber_t agno,
xfs_agblock_t agbno)
{
- if (agno < (sbp->sb_agcount - 1))
- return (agbno >= sbp->sb_agblocks);
- if (agno == (sbp->sb_agcount - 1))
+ /* in all cases bno >= agblocks is bad */
+ if (agbno >= sbp->sb_agblocks)
+ return 1;
+ /* last ag may be smaller */
+ if (agno == (sbp->sb_agcount - 1))
return (agbno >= (sbp->sb_dblocks -
- ((sbp->sb_agcount - 1) * sbp->sb_agblocks)));
+ ((xfs_drfsbno_t)(sbp->sb_agcount - 1) *
+ sbp->sb_agblocks)));
return 1;
}
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next reply other threads:[~2009-07-01 20:32 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-07-01 20:33 Eric Sandeen [this message]
2009-07-01 22:15 ` [PATCH] xfs_repair: fix verify_ag_bno() overflow Eric Sandeen
2009-07-02 4:13 ` [PATCH V3] xfs_repair: fix agcount*agblocks overflows Eric Sandeen
2009-07-02 5:24 ` Felix Blyakher
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