[PATCH 06/14] xfs: check that bc_nlevels never overflows

Darrick J. Wong
2021-09-18T01:29:44Z

From: Darrick J. Wong <djwong@kernel.org>

Warn if we ever bump nlevels higher than the allowed maximum cursor
height.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
---
fs/xfs/libxfs/xfs_btree.c | 2 ++
fs/xfs/libxfs/xfs_btree_staging.c | 2 ++
2 files changed, 4 insertions(+)

diff --git a/fs/xfs/libxfs/xfs_btree.c b/fs/xfs/libxfs/xfs_btree.c
index b0cce0932f02..bc4e49f0456a 100644
--- a/fs/xfs/libxfs/xfs_btree.c
+++ b/fs/xfs/libxfs/xfs_btree.c
@@ -2933,6 +2933,7 @@ xfs_btree_new_iroot(
be16_add_cpu(&block->bb_level, 1);
xfs_btree_set_numrecs(block, 1);
cur->bc_nlevels++;
+ ASSERT(cur->bc_nlevels <= XFS_BTREE_MAXLEVELS);
cur->bc_ptrs[level + 1] = 1;

kp = xfs_btree_key_addr(cur, 1, block);
@@ -3096,6 +3097,7 @@ xfs_btree_new_root(
xfs_btree_setbuf(cur, cur->bc_nlevels, nbp);
cur->bc_ptrs[cur->bc_nlevels] = nptr;
cur->bc_nlevels++;
+ ASSERT(cur->bc_nlevels <= XFS_BTREE_MAXLEVELS);
*stat = 1;
return 0;
error0:
diff --git a/fs/xfs/libxfs/xfs_btree_staging.c b/fs/xfs/libxfs/xfs_btree_staging.c
index ac9e80152b5c..26143297bb7b 100644
--- a/fs/xfs/libxfs/xfs_btree_staging.c
+++ b/fs/xfs/libxfs/xfs_btree_staging.c
@@ -703,6 +703,7 @@ xfs_btree_bload_compute_geometry(
* block-based btree level.
*/
cur->bc_nlevels++;
+ ASSERT(cur->bc_nlevels <= XFS_BTREE_MAXLEVELS);
xfs_btree_bload_level_geometry(cur, bbl, level,
nr_this_level, &avg_per_block,
&level_blocks, &dontcare64);
@@ -718,6 +719,7 @@ xfs_btree_bload_compute_geometry(

/* Otherwise, we need another level of btree. */
cur->bc_nlevels++;
+ ASSERT(cur->bc_nlevels <= XFS_BTREE_MAXLEVELS);
}

nr_blocks += level_blocks;