[PATCH 5.10.y] btrfs: tree-checker: fix the incorrect inode ref size check

[Sasha Levin <sashal@kernel.org>]

From: Qu Wenruo <wqu@suse.com>

[ Upstream commit 96fa515e70f3e4b98685ef8cac9d737fc62f10e1 ]

[BUG]
Inside check_inode_ref(), we need to make sure every structure,
including the btrfs_inode_extref header, is covered by the item.  But
our code is incorrectly using "sizeof(iref)", where @iref is just a
pointer.

This means "sizeof(iref)" will always be "sizeof(void *)", which is much
smaller than "sizeof(struct btrfs_inode_extref)".

This will allow some bad inode extrefs to sneak in, defeating tree-checker.

[FIX]
Fix the typo by calling "sizeof(*iref)", which is the same as
"sizeof(struct btrfs_inode_extref)", and will be the correct behavior we
want.

Fixes: 71bf92a9b877 ("btrfs: tree-checker: Add check for INODE_REF")
CC: stable@vger.kernel.org # 6.1+
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
[ Added unlikely() ]
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 fs/btrfs/tree-checker.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/fs/btrfs/tree-checker.c b/fs/btrfs/tree-checker.c
index 35b94fe5e78e7..c28bb37688c61 100644
--- a/fs/btrfs/tree-checker.c
+++ b/fs/btrfs/tree-checker.c
@@ -1545,10 +1545,10 @@ static int check_inode_ref(struct extent_buffer *leaf,
 	while (ptr < end) {
 		u16 namelen;
 
-		if (ptr + sizeof(iref) > end) {
+		if (unlikely(ptr + sizeof(*iref) > end)) {
 			inode_ref_err(leaf, slot,
 			"inode ref overflow, ptr %lu end %lu inode_ref_size %zu",
-				ptr, end, sizeof(iref));
+				ptr, end, sizeof(*iref));
 			return -EUCLEAN;
 		}
 
-- 
2.51.0