Commit 7d2a894d authored by Rémi Denis-Courmont's avatar Rémi Denis-Courmont Committed by Paolo Abeni
Browse files

phonet/pep: fix racy skb_queue_empty() use 



The receive queues are protected by their respective spin-lock, not
the socket lock. This could lead to skb_peek() unexpectedly
returning NULL or a pointer to an already dequeued socket buffer.

Fixes: 9641458d ("Phonet: Pipe End Point for Phonet Pipes protocol")
Signed-off-by: default avatarRémi Denis-Courmont <courmisch@gmail.com>
Link: https://lore.kernel.org/r/20240218081214.4806-2-remi@remlab.net


Signed-off-by: default avatarPaolo Abeni <pabeni@redhat.com>
parent 3b2d9bc4

net/phonet/pep.c

+32 −9
Original line number Diff line number Diff line
@@ -917,6 +917,37 @@ static int pep_sock_enable(struct sock *sk, struct sockaddr *addr, int len) 
	return 0;

}



static unsigned int pep_first_packet_length(struct sock *sk)

{

	struct pep_sock *pn = pep_sk(sk);

	struct sk_buff_head *q;

	struct sk_buff *skb;

	unsigned int len = 0;

	bool found = false;



	if (sock_flag(sk, SOCK_URGINLINE)) {

		q = &pn->ctrlreq_queue;

		spin_lock_bh(&q->lock);

		skb = skb_peek(q);

		if (skb) {

			len = skb->len;

			found = true;

		}

		spin_unlock_bh(&q->lock);

	}



	if (likely(!found)) {

		q = &sk->sk_receive_queue;

		spin_lock_bh(&q->lock);

		skb = skb_peek(q);

		if (skb)

			len = skb->len;

		spin_unlock_bh(&q->lock);

	}



	return len;

}



static int pep_ioctl(struct sock *sk, int cmd, int *karg)

{

	struct pep_sock *pn = pep_sk(sk);
@@ -929,15 +960,7 @@ static int pep_ioctl(struct sock *sk, int cmd, int *karg) 
			break;

		}



		lock_sock(sk);

		if (sock_flag(sk, SOCK_URGINLINE) &&

		    !skb_queue_empty(&pn->ctrlreq_queue))

			*karg = skb_peek(&pn->ctrlreq_queue)->len;

		else if (!skb_queue_empty(&sk->sk_receive_queue))

			*karg = skb_peek(&sk->sk_receive_queue)->len;

		else

			*karg = 0;

		release_sock(sk);

		*karg = pep_first_packet_length(sk);

		ret = 0;

		break;