[PATCH] jfs: Issue a warning when leafidx is too large

[Edward Adam Davis]

When it is clear that leafidx is too large, a warn is triggered to
distinguish it from other sizes.

Reported-by: syzbot+077d9ebda84f426a6a1e@xxxxxxxxxxxxxxxxxxxxxxxxx
Closes: https://syzkaller.appspot.com/bug?extid=077d9ebda84f426a6a1e
Signed-off-by: Edward Adam Davis <eadavis@xxxxxx>
---
 fs/jfs/jfs_dmap.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/fs/jfs/jfs_dmap.c b/fs/jfs/jfs_dmap.c
index 35e063c9f3a4..7e3c5f6826d8 100644
--- a/fs/jfs/jfs_dmap.c
+++ b/fs/jfs/jfs_dmap.c
@@ -2856,9 +2856,13 @@ static int dbJoin(dmtree_t *tp, int leafno, int newval, bool is_ctl)
 static void dbAdjTree(dmtree_t *tp, int leafno, int newval, bool is_ctl)
 {
 	int lp, pp, k;
-	int max, size;
+	int max, size, max_idx;
 
 	size = is_ctl ? CTLTREESIZE : TREESIZE;
+	max_idx = is_ctl ? LPERCTL : LPERDMAP;
+
+	if (WARN_ON_ONCE(le32_to_cpu(tp->dmt_leafidx) >= max_idx))
+		return;
 
 	/* pick up the index of the leaf for this leafno.
 	 */
-- 
2.43.0