From b465518dc27da1ed74b8cbada4659708aac35adb Mon Sep 17 00:00:00 2001 From: Stefano Garzarella Date: Fri, 24 Mar 2023 12:54:50 +0100 Subject: vsock/loopback: use only sk_buff_head.lock to protect the packet queue pkt_list_lock was used before commit 71dc9ec9ac7d ("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: 71dc9ec9ac7d ("virtio/vsock: replace virtio_vsock_pkt with sk_buff") Cc: bobby.eshleman@bytedance.com Reported-and-tested-by: syzbot+befff0a9536049e7902e@syzkaller.appspotmail.com Signed-off-by: Stefano Garzarella Reviewed-by: Bobby Eshleman Reviewed-by: Arseniy Krasnov Signed-off-by: David S. Miller --- net/vmw_vsock/vsock_loopback.c | 10 ++-------- 1 file changed, 2 insertions(+), 8 deletions(-) (limited to 'net') diff --git a/net/vmw_vsock/vsock_loopback.c b/net/vmw_vsock/vsock_loopback.c index 671e03240fc5..89905c092645 100644 --- a/net/vmw_vsock/vsock_loopback.c +++ b/net/vmw_vsock/vsock_loopback.c @@ -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); } -- cgit v1.2.3