[XFS] Prevent xfs_bmap_check_leaf_extents() referencing unmapped memory. (2abdb8c8) · Commits · 戴 / test

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 <lachlan@sgi.com> Signed-off-by:

Christoph Hellwig <hch@infradead.org>

fs/xfs/xfs_bmap.c

+6 −9

Original line number	Diff line number	Diff line
		@@ -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;

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