xfs: fix integer overflow in bmap intent sort comparator

Long Li · cmaiolino · commit 362c49098086 · 2026-03-11T13:21:42.000+01:00
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: 9f3afb5 ("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>
diff --git a/fs/xfs/xfs_bmap_item.c b/fs/xfs/xfs_bmap_item.c
@@ -245,7 +245,7 @@ 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 cmp_int(ba->bi_owner->i_ino, bb->bi_owner->i_ino);
 }
 
 /* Log bmap updates in the intent item. */

Original file line number	Diff line number	Diff line change
`@@ -245,7 +245,7 @@ xfs_bmap_update_diff_items(`
`245`	`245`	`struct xfs_bmap_intent *ba = bi_entry(a);`
`246`	`246`	`struct xfs_bmap_intent *bb = bi_entry(b);`
`247`	`247`
`248`		`- return ba->bi_owner->i_ino - bb->bi_owner->i_ino;`
	`248`	`+ return cmp_int(ba->bi_owner->i_ino, bb->bi_owner->i_ino);`
`249`	`249`	`}`
`250`	`250`
`251`	`251`	`/* Log bmap updates in the intent item. */`