This is a note to let you know that I've just added the patch titled vsock/loopback: use only sk_buff_head.lock to protect the packet queue to the 6.1-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: vsock-loopback-use-only-sk_buff_head.lock-to-protect-the-packet-queue.patch and it can be found in the queue-6.1 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From b465518dc27da1ed74b8cbada4659708aac35adb Mon Sep 17 00:00:00 2001 From: Stefano Garzarella <sgarzare@xxxxxxxxxx> Date: Fri, 24 Mar 2023 12:54:50 +0100 Subject: vsock/loopback: use only sk_buff_head.lock to protect the packet queue From: Stefano Garzarella <sgarzare@xxxxxxxxxx> commit b465518dc27da1ed74b8cbada4659708aac35adb upstream. 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@xxxxxxxxxxxxx Reported-and-tested-by: syzbot+befff0a9536049e7902e@xxxxxxxxxxxxxxxxxxxxxxxxx Signed-off-by: Stefano Garzarella <sgarzare@xxxxxxxxxx> Reviewed-by: Bobby Eshleman <bobby.eshleman@xxxxxxxxxxxxx> Reviewed-by: Arseniy Krasnov <AVKrasnov@xxxxxxxxxxxxxx> Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- net/vmw_vsock/vsock_loopback.c | 10 ++-------- 1 file changed, 2 insertions(+), 8 deletions(-) --- 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(struc 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 w 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(vo 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(v 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); } Patches currently in stable-queue which might be from sgarzare@xxxxxxxxxx are queue-6.1/virtio-vsock-fix-header-length-on-skb-merging.patch queue-6.1/virtio-vsock-fix-leaks-due-to-missing-skb-owner.patch queue-6.1/virtio-vsock-don-t-drop-skbuff-on-copy-failure.patch queue-6.1/virtio-vsock-replace-virtio_vsock_pkt-with-sk_buff.patch queue-6.1/virtio-vsock-don-t-use-skbuff-state-to-account-credit.patch queue-6.1/virtio-vsock-remove-redundant-skb_pull-call.patch queue-6.1/vsock-loopback-use-only-sk_buff_head.lock-to-protect-the-packet-queue.patch queue-6.1/vsock-virtio-remove-socket-from-connected-bound-list.patch queue-6.1/virtio-vsock-fix-uninit-value-in-virtio_transport_recv_pkt.patch