5.15-stable review patch. If anyone has any objections, please let me know. ------------------ From: Ryusuke Konishi <konishi.ryusuke@xxxxxxxxx> [ Upstream commit 111b812d3662f3a1b831d19208f83aa711583fe6 ] Due to the nature of b-trees, nilfs2 itself and admin tools such as mkfs.nilfs2 will never create an intermediate b-tree node block with 0 child nodes, nor will they delete (key, pointer)-entries that would result in such a state. However, it is possible that a b-tree node block is corrupted on the backing device and is read with 0 child nodes. Because operation is not guaranteed if the number of child nodes is 0 for intermediate node blocks other than the root node, modify nilfs_btree_node_broken(), which performs sanity checks when reading a b-tree node block, so that such cases will be judged as metadata corruption. Link: https://lkml.kernel.org/r/20240904081401.16682-3-konishi.ryusuke@xxxxxxxxx Fixes: 17c76b0104e4 ("nilfs2: B-tree based block mapping") Signed-off-by: Ryusuke Konishi <konishi.ryusuke@xxxxxxxxx> Cc: Lizhi Xu <lizhi.xu@xxxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> --- fs/nilfs2/btree.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/fs/nilfs2/btree.c b/fs/nilfs2/btree.c index fbb6ec56843f4..4de33c534e470 100644 --- a/fs/nilfs2/btree.c +++ b/fs/nilfs2/btree.c @@ -350,7 +350,7 @@ static int nilfs_btree_node_broken(const struct nilfs_btree_node *node, if (unlikely(level < NILFS_BTREE_LEVEL_NODE_MIN || level >= NILFS_BTREE_LEVEL_MAX || (flags & NILFS_BTREE_NODE_ROOT) || - nchildren < 0 || + nchildren <= 0 || nchildren > NILFS_BTREE_NODE_NCHILDREN_MAX(size))) { nilfs_crit(inode->i_sb, "bad btree node (ino=%lu, blocknr=%llu): level = %d, flags = 0x%x, nchildren = %d", -- 2.43.0
