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: [email protected]
Reported-and-tested-by: [email protected]
Signed-off-by: Stefano Garzarella <[email protected]>
---
net/vmw_vsock/vsock_loopback.c | 10 ++--------
1 file changed, 2 insertions(+), 8 deletions(-)
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);
}
--
2.39.2
On 24.03.2023 14:54, Stefano Garzarella wrote:
> 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: [email protected]
> Reported-and-tested-by: [email protected]
> Signed-off-by: Stefano Garzarella <[email protected]>
> ---
> net/vmw_vsock/vsock_loopback.c | 10 ++--------
> 1 file changed, 2 insertions(+), 8 deletions(-)
Reviewed-by: Arseniy Krasnov <[email protected]>
>
> 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);
> }
On Fri, Mar 24, 2023 at 12:54:50PM +0100, Stefano Garzarella wrote:
> 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: [email protected]
> Reported-and-tested-by: [email protected]
> Signed-off-by: Stefano Garzarella <[email protected]>
> ---
> net/vmw_vsock/vsock_loopback.c | 10 ++--------
> 1 file changed, 2 insertions(+), 8 deletions(-)
>
> 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);
> }
> --
> 2.39.2
>
Makes sense to me. Thanks for getting to this so fast.
Best,
Bobby
Reviewed-by: Bobby Eshleman <[email protected]>
Hello:
This patch was applied to netdev/net.git (main)
by David S. Miller <[email protected]>:
On Fri, 24 Mar 2023 12:54:50 +0100 you wrote:
> 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.
>
> [...]
Here is the summary with links:
- [net] vsock/loopback: use only sk_buff_head.lock to protect the packet queue
https://git.kernel.org/netdev/net/c/b465518dc27d
You are awesome, thank you!
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