From 7341e9a5850d6fe9ad1e6a93d9a6c0d3cc82e371 Mon Sep 17 00:00:00 2001 From: Ryusuke Konishi Date: Fri, 25 Oct 2024 10:58:30 +0800 Subject: [PATCH] nilfs2: fix potential oob read in nilfs_btree_check_delete() stable inclusion from stable-v6.6.53 commit 257f9e5185eb6de83377caea686c306e22e871f2 category: bugfix bugzilla: https://gitee.com/src-openeuler/kernel/issues/IAYQRO CVE: CVE-2024-47757 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?h=tags/v6.6.54&id=257f9e5185eb6de83377caea686c306e22e871f2 -------------------------------- [ Upstream commit f9c96351aa6718b42a9f42eaf7adce0356bdb5e8 ] The function nilfs_btree_check_delete(), which checks whether degeneration to direct mapping occurs before deleting a b-tree entry, causes memory access outside the block buffer when retrieving the maximum key if the root node has no entries. This does not usually happen because b-tree mappings with 0 child nodes are never created by mkfs.nilfs2 or nilfs2 itself. However, it can happen if the b-tree root node read from a device is configured that way, so fix this potential issue by adding a check for that case. Link: https://lkml.kernel.org/r/20240904081401.16682-4-konishi.ryusuke@gmail.com Fixes: 17c76b0104e4 ("nilfs2: B-tree based block mapping") Signed-off-by: Ryusuke Konishi Cc: Lizhi Xu Signed-off-by: Andrew Morton Signed-off-by: Sasha Levin Signed-off-by: Long Li --- fs/nilfs2/btree.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) diff --git a/fs/nilfs2/btree.c b/fs/nilfs2/btree.c index a426e4e2acda..43a180be9381 100644 --- a/fs/nilfs2/btree.c +++ b/fs/nilfs2/btree.c @@ -1659,13 +1659,16 @@ static int nilfs_btree_check_delete(struct nilfs_bmap *btree, __u64 key) int nchildren, ret; root = nilfs_btree_get_root(btree); + nchildren = nilfs_btree_node_get_nchildren(root); + if (unlikely(nchildren == 0)) + return 0; + switch (nilfs_btree_height(btree)) { case 2: bh = NULL; node = root; break; case 3: - nchildren = nilfs_btree_node_get_nchildren(root); if (nchildren > 1) return 0; ptr = nilfs_btree_node_get_ptr(root, nchildren - 1, @@ -1674,12 +1677,12 @@ static int nilfs_btree_check_delete(struct nilfs_bmap *btree, __u64 key) if (ret < 0) return ret; node = (struct nilfs_btree_node *)bh->b_data; + nchildren = nilfs_btree_node_get_nchildren(node); break; default: return 0; } - nchildren = nilfs_btree_node_get_nchildren(node); maxkey = nilfs_btree_node_get_key(node, nchildren - 1); nextmaxkey = (nchildren > 1) ? nilfs_btree_node_get_key(node, nchildren - 2) : 0; -- Gitee