From 2abdb8c88110bab78bfe17e51346e735560daa02 Mon Sep 17 00:00:00 2001 From: Lachlan McIlroy Date: Thu, 27 Mar 2008 18:01:14 +1100 Subject: [PATCH] [XFS] Prevent xfs_bmap_check_leaf_extents() referencing unmapped memory. While investigating the extent corruption bug I ran into this bug in debug only code. xfs_bmap_check_leaf_extents() loops through the leaf blocks of the extent btree checking that every extent is entirely before the next extent. It also compares the last extent in the previous block to the first extent in the current block when the previous block has been released and potentially unmapped. So take a copy of the last extent instead of a pointer. Also move the last extent check out of the loop because we only need to do it once. SGI-PV: 976035 SGI-Modid: xfs-linux-melb:xfs-kern:30718a Signed-off-by: Lachlan McIlroy Signed-off-by: Christoph Hellwig --- fs/xfs/xfs_bmap.c | 15 ++++++--------- 1 file changed, 6 insertions(+), 9 deletions(-) diff --git a/fs/xfs/xfs_bmap.c b/fs/xfs/xfs_bmap.c index bce8e3bd8ad1..7d683e0b8ef7 100644 --- a/fs/xfs/xfs_bmap.c +++ b/fs/xfs/xfs_bmap.c @@ -6194,7 +6194,7 @@ xfs_bmap_check_leaf_extents( xfs_mount_t *mp; /* file system mount structure */ __be64 *pp; /* pointer to block address */ xfs_bmbt_rec_t *ep; /* pointer to current extent */ - xfs_bmbt_rec_t *lastp; /* pointer to previous extent */ + xfs_bmbt_rec_t last = {0, 0}; /* last extent in prev block */ xfs_bmbt_rec_t *nextp; /* pointer to next extent */ int bp_release = 0; @@ -6264,7 +6264,6 @@ xfs_bmap_check_leaf_extents( /* * Loop over all leaf nodes checking that all extents are in the right order. */ - lastp = NULL; for (;;) { xfs_fsblock_t nextbno; xfs_extnum_t num_recs; @@ -6285,18 +6284,16 @@ xfs_bmap_check_leaf_extents( */ ep = XFS_BTREE_REC_ADDR(xfs_bmbt, block, 1); + if (i) { + xfs_btree_check_rec(XFS_BTNUM_BMAP, &last, ep); + } for (j = 1; j < num_recs; j++) { nextp = XFS_BTREE_REC_ADDR(xfs_bmbt, block, j + 1); - if (lastp) { - xfs_btree_check_rec(XFS_BTNUM_BMAP, - (void *)lastp, (void *)ep); - } - xfs_btree_check_rec(XFS_BTNUM_BMAP, (void *)ep, - (void *)(nextp)); - lastp = ep; + xfs_btree_check_rec(XFS_BTNUM_BMAP, ep, nextp); ep = nextp; } + last = *ep; i += num_recs; if (bp_release) { bp_release = 0; -- 2.20.1