[PATCH V2] jfs: check if leafidx greater than num leaves per dmap tree

[Edward Adam Davis]

syzbot report a out of bounds in dbSplit, it because dmt_leafidx greater
than num leaves per dmap tree, add a checking for dmt_leafidx in dbFindLeaf.

Reported-and-tested-by: syzbot+dca05492eff41f604890@xxxxxxxxxxxxxxxxxxxxxxxxx
Closes: https://syzkaller.appspot.com/bug?extid=dca05492eff41f604890
Signed-off-by: Edward Adam Davis <eadavis@xxxxxx>
---
 fs/jfs/jfs_dmap.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/fs/jfs/jfs_dmap.c b/fs/jfs/jfs_dmap.c
index cb3cda1390ad..516bac758053 100644
--- a/fs/jfs/jfs_dmap.c
+++ b/fs/jfs/jfs_dmap.c
@@ -2976,6 +2976,8 @@ static int dbFindLeaf(dmtree_t *tp, int l2nb, int *leafidx, bool is_ctl)
 		 */
 		assert(n < 4);
 	}
+	if (le32_to_cpu(tp->dmt_leafidx) >= LPERDMAP)
+		return -ENOSPC;
 
 	/* set the return to the leftmost leaf describing sufficient
 	 * free space.
-- 
2.43.0