[PATCH v1] bcachefs: add check for btree id against max in try read node

[Piotr Zalewski]

Add check for read node's btree_id against BTREE_ID_NR_MAX in
try_read_btree_node to prevent triggering EBUG_ON condition in
bch2_btree_id_root[1].

[1] https://syzkaller.appspot.com/bug?extid=cf7b2215b5d70600ec00

Reported-by: syzbot+cf7b2215b5d70600ec00@xxxxxxxxxxxxxxxxxxxxxxxxx
Closes: https://syzkaller.appspot.com/bug?extid=cf7b2215b5d70600ec00
Fixes: 4409b8081d16 ("bcachefs: Repair pass for scanning for btree nodes")
Signed-off-by: Piotr Zalewski <pZ010001011111@xxxxxxxxx>
---
 fs/bcachefs/btree_node_scan.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/fs/bcachefs/btree_node_scan.c b/fs/bcachefs/btree_node_scan.c
index b28c649c6838..a24b4004e8f0 100644
--- a/fs/bcachefs/btree_node_scan.c
+++ b/fs/bcachefs/btree_node_scan.c
@@ -171,6 +171,9 @@ static void try_read_btree_node(struct find_btree_nodes *f, struct bch_dev *ca,
 	if (BTREE_NODE_LEVEL(bn) >= BTREE_MAX_DEPTH)
 		return;
 
+	if (BTREE_NODE_ID(bn) >= BTREE_ID_NR_MAX)
+		return;
+
 	rcu_read_lock();
 	struct found_btree_node n = {
 		.btree_id	= BTREE_NODE_ID(bn),
-- 
2.46.2