Commit b465518d authored by Stefano Garzarella's avatar Stefano Garzarella Committed by David S. Miller
Browse files

vsock/loopback: use only sk_buff_head.lock to protect the packet queue 



pkt_list_lock was used before commit 71dc9ec9 ("virtio/vsock:
replace virtio_vsock_pkt with sk_buff") to protect the packet queue.
After that commit we switched to sk_buff and we are using
sk_buff_head.lock in almost every place to protect the packet queue
except in vsock_loopback_work() when we call skb_queue_splice_init().

As reported by syzbot, this caused unlocked concurrent access to the
packet queue between vsock_loopback_work() and
vsock_loopback_cancel_pkt() since it is not holding pkt_list_lock.

With the introduction of sk_buff_head, pkt_list_lock is redundant and
can cause confusion, so let's remove it and use sk_buff_head.lock
everywhere to protect the packet queue access.

Fixes: 71dc9ec9 ("virtio/vsock: replace virtio_vsock_pkt with sk_buff")
Cc: bobby.eshleman@bytedance.com
Reported-and-tested-by: default avatar <syzbot+befff0a9536049e7902e@syzkaller.appspotmail.com>
Signed-off-by: default avatarStefano Garzarella <sgarzare@redhat.com>
Reviewed-by: default avatarBobby Eshleman <bobby.eshleman@bytedance.com>
Reviewed-by: default avatarArseniy Krasnov <AVKrasnov@sberdevices.ru>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 62203584

net/vmw_vsock/vsock_loopback.c

+2 −8
Original line number Diff line number Diff line
@@ -15,7 +15,6 @@ 
struct vsock_loopback {

	struct workqueue_struct *workqueue;



	spinlock_t pkt_list_lock; /* protects pkt_list */

	struct sk_buff_head pkt_queue;

	struct work_struct pkt_work;

};
@@ -32,9 +31,7 @@ static int vsock_loopback_send_pkt(struct sk_buff *skb) 
	struct vsock_loopback *vsock = &the_vsock_loopback;

	int len = skb->len;



	spin_lock_bh(&vsock->pkt_list_lock);

	skb_queue_tail(&vsock->pkt_queue, skb);

	spin_unlock_bh(&vsock->pkt_list_lock);



	queue_work(vsock->workqueue, &vsock->pkt_work);
@@ -113,9 +110,9 @@ static void vsock_loopback_work(struct work_struct *work) 


	skb_queue_head_init(&pkts);



	spin_lock_bh(&vsock->pkt_list_lock);

	spin_lock_bh(&vsock->pkt_queue.lock);

	skb_queue_splice_init(&vsock->pkt_queue, &pkts);

	spin_unlock_bh(&vsock->pkt_list_lock);

	spin_unlock_bh(&vsock->pkt_queue.lock);



	while ((skb = __skb_dequeue(&pkts))) {

		virtio_transport_deliver_tap_pkt(skb);
@@ -132,7 +129,6 @@ static int __init vsock_loopback_init(void) 
	if (!vsock->workqueue)

		return -ENOMEM;



	spin_lock_init(&vsock->pkt_list_lock);

	skb_queue_head_init(&vsock->pkt_queue);

	INIT_WORK(&vsock->pkt_work, vsock_loopback_work);
@@ -156,9 +152,7 @@ static void __exit vsock_loopback_exit(void) 


	flush_work(&vsock->pkt_work);



	spin_lock_bh(&vsock->pkt_list_lock);

	virtio_vsock_skb_queue_purge(&vsock->pkt_queue);

	spin_unlock_bh(&vsock->pkt_list_lock);



	destroy_workqueue(vsock->workqueue);

}