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[XFS] Fix use-after-free with buffers 

We have a use-after-free issue where log completions access buffers via
the buffer log item and the buffer has already been freed. Fix this by
taking a reference on the buffer when attaching the buffer log item and
release the hold when the buffer log item is detached and we no longer
need the buffer. Also create a new function xfs_buf_item_free() to combine
some common code.

SGI-PV: 985757

SGI-Modid: xfs-linux-melb:xfs-kern:32025a

Signed-off-by: Lachlan McIlroy <lachlan@sgi.com>
Signed-off-by: Christoph Hellwig <hch@infradead.org>
This commit is contained in:
Lachlan McIlroy 2008-09-17 16:52:13 +10:00 committed by Lachlan McIlroy
parent f9114eba1e
commit e1f5dbd707
1 changed files with 20 additions and 24 deletions
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44
fs/xfs/xfs_buf_item.c
View File

@ -732,6 +732,7 @@ xfs_buf_item_init(
bip->bli_item.li_ops = &xfs_buf_item_ops;
bip->bli_item.li_mountp = mp;
bip->bli_buf = bp;
xfs_buf_hold(bp);
bip->bli_format.blf_type = XFS_LI_BUF;
bip->bli_format.blf_blkno = (__int64_t)XFS_BUF_ADDR(bp);
bip->bli_format.blf_len = (ushort)BTOBB(XFS_BUF_COUNT(bp));
@ -867,6 +868,21 @@ xfs_buf_item_dirty(
return (bip->bli_flags & XFS_BLI_DIRTY);
}
STATIC void
xfs_buf_item_free(
xfs_buf_log_item_t *bip)
{
#ifdef XFS_TRANS_DEBUG
kmem_free(bip->bli_orig);
kmem_free(bip->bli_logged);
#endif /* XFS_TRANS_DEBUG */
#ifdef XFS_BLI_TRACE
ktrace_free(bip->bli_trace);
#endif
kmem_zone_free(xfs_buf_item_zone, bip);
}
/*
* This is called when the buf log item is no longer needed. It should
* free the buf log item associated with the given buffer and clear
@ -887,18 +903,8 @@ xfs_buf_item_relse(
(XFS_BUF_IODONE_FUNC(bp) != NULL)) {
XFS_BUF_CLR_IODONE_FUNC(bp);
}
#ifdef XFS_TRANS_DEBUG
kmem_free(bip->bli_orig);
bip->bli_orig = NULL;
kmem_free(bip->bli_logged);
bip->bli_logged = NULL;
#endif /* XFS_TRANS_DEBUG */
#ifdef XFS_BLI_TRACE
ktrace_free(bip->bli_trace);
#endif
kmem_zone_free(xfs_buf_item_zone, bip);
xfs_buf_rele(bp);
xfs_buf_item_free(bip);
}
@ -1120,6 +1126,7 @@ xfs_buf_iodone(
ASSERT(bip->bli_buf == bp);
xfs_buf_rele(bp);
mp = bip->bli_item.li_mountp;
/*
@ -1136,18 +1143,7 @@ xfs_buf_iodone(
* xfs_trans_delete_ail() drops the AIL lock.
*/
xfs_trans_delete_ail(mp, (xfs_log_item_t *)bip);
#ifdef XFS_TRANS_DEBUG
kmem_free(bip->bli_orig);
bip->bli_orig = NULL;
kmem_free(bip->bli_logged);
bip->bli_logged = NULL;
#endif /* XFS_TRANS_DEBUG */
#ifdef XFS_BLI_TRACE
ktrace_free(bip->bli_trace);
#endif
kmem_zone_free(xfs_buf_item_zone, bip);
xfs_buf_item_free(bip);
}
#if defined(XFS_BLI_TRACE)