[PATCH 6.12 272/460] xfs: fix integer overflow in bmap intent sort comparator

Greg Kroah-Hartman
2026-03-23T14:42:50Z

6.12-stable review patch. If anyone has any objections, please let me know.

------------------

From: Long Li <leo.lilong@huawei.com>

[ Upstream commit 362c490980867930a098b99f421268fbd7ca05fd ]

xfs_bmap_update_diff_items() sorts bmap intents by inode number using
a subtraction of two xfs_ino_t (uint64_t) values, with the result
truncated to int. This is incorrect when two inode numbers differ by
more than INT_MAX (2^31 - 1), which is entirely possible on large XFS
filesystems.

Fix this by replacing the subtraction with cmp_int().

Cc: <stable@vger.kernel.org> # v4.9
Fixes: 9f3afb57d5f1 ("xfs: implement deferred bmbt map/unmap operations")
Signed-off-by: Long Li <leo.lilong@huawei.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Carlos Maiolino <cem@kernel.org>
[ No cmp_int() ]
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
fs/xfs/xfs_bmap_item.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

--- a/fs/xfs/xfs_bmap_item.c
+++ b/fs/xfs/xfs_bmap_item.c
@@ -237,7 +237,8 @@ xfs_bmap_update_diff_items(
struct xfs_bmap_intent *ba = bi_entry(a);
struct xfs_bmap_intent *bb = bi_entry(b);

- return ba->bi_owner->i_ino - bb->bi_owner->i_ino;
+ return ((ba->bi_owner->i_ino > bb->bi_owner->i_ino) -
+ (ba->bi_owner->i_ino < bb->bi_owner->i_ino));
}

/* Log bmap updates in the intent item. */