please test null ptr defref in l2cap_sock_recv_cb
#syz test https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git cc8ed4d0a848
diff --git a/net/bluetooth/l2cap_sock.c b/net/bluetooth/l2cap_sock.c
index 6db60946c627..9938d3681772 100644
--- a/net/bluetooth/l2cap_sock.c
+++ b/net/bluetooth/l2cap_sock.c
@@ -1413,6 +1413,8 @@ static int l2cap_sock_release(struct socket *sock)
l2cap_chan_hold(chan);
l2cap_chan_lock(chan);
+ if (refcount_read(&sk->sk_refcnt) == 1)
+ chan->data = NULL;
sock_orphan(sk);
l2cap_sock_kill(sk);
@@ -1481,12 +1483,23 @@ static struct l2cap_chan *l2cap_sock_new_connection_cb(struct l2cap_chan *chan)
static int l2cap_sock_recv_cb(struct l2cap_chan *chan, struct sk_buff *skb)
{
- struct sock *sk = chan->data;
- struct l2cap_pinfo *pi = l2cap_pi(sk);
+ struct sock *sk;
+ struct l2cap_pinfo *pi;
int err;
- lock_sock(sk);
+ l2cap_chan_hold(chan);
+ l2cap_chan_lock(chan);
+ sk = chan->data;
+
+ if (!sk) {
+ printk("%s\n", __func__);
+ l2cap_chan_unlock(chan);
+ l2cap_chan_put(chan);
+ return -ENXIO;
+ }
+ pi = l2cap_pi(sk);
+ lock_sock(sk);
if (chan->mode == L2CAP_MODE_ERTM && !list_empty(&pi->rx_busy)) {
err = -ENOMEM;
goto done;
@@ -1535,6 +1548,8 @@ static int l2cap_sock_recv_cb(struct l2cap_chan *chan, struct sk_buff *skb)
done:
release_sock(sk);
+ l2cap_chan_unlock(chan);
+ l2cap_chan_put(chan);
return err;
}
Hello,
syzbot has tested the proposed patch and the reproducer did not trigger any issue:
Reported-and-tested-by: [email protected]
Tested on:
commit: cc8ed4d0 Merge tag 'drm-fixes-2024-06-01' of https://g..
git tree: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
console output: https://syzkaller.appspot.com/x/log.txt?x=13ae3bf6980000
kernel config: https://syzkaller.appspot.com/x/.config?x=47d282ddffae809f
dashboard link: https://syzkaller.appspot.com/bug?extid=b7f6f8c9303466e16c8a
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
patch: https://syzkaller.appspot.com/x/patch.diff?x=1716a4da980000
Note: testing is done by a robot and is best-effort only.