bcachefs: add check for btree id against max in try read node

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@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=cf7b2215b5d70600ec00
Fixes: 4409b8081d16 ("bcachefs: Repair pass for scanning for btree nodes")
Signed-off-by: Piotr Zalewski <pZ010001011111@proton.me>
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

diff --git a/fs/bcachefs/btree_node_scan.c b/fs/bcachefs/btree_node_scan.c
index 1e694fedc5da049895fa4cb692ca0799ff7f9d5e..a7aedb134e9f8c23e32dea792023cea871429bf4 100644 (file)
--- 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),