This is a note to let you know that I've just added the patch titled xen/netback: don't call kfree_skb() with interrupts disabled to the 4.9-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: xen-netback-don-t-call-kfree_skb-with-interrupts-dis.patch and it can be found in the queue-4.9 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. commit 4449f17d041a0b8671316feaff0691d20876b54d Author: Juergen Gross <jgross@xxxxxxxx> Date: Tue Dec 6 08:54:24 2022 +0100 xen/netback: don't call kfree_skb() with interrupts disabled [ Upstream commit 74e7e1efdad45580cc3839f2a155174cf158f9b5 ] It is not allowed to call kfree_skb() from hardware interrupt context or with interrupts being disabled. So remove kfree_skb() from the spin_lock_irqsave() section and use the already existing "drop" label in xenvif_start_xmit() for dropping the SKB. At the same time replace the dev_kfree_skb() call there with a call of dev_kfree_skb_any(), as xenvif_start_xmit() can be called with disabled interrupts. This is XSA-424 / CVE-2022-42328 / CVE-2022-42329. Fixes: be81992f9086 ("xen/netback: don't queue unlimited number of packages") Reported-by: Yang Yingliang <yangyingliang@xxxxxxxxxx> Signed-off-by: Juergen Gross <jgross@xxxxxxxx> Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx> Signed-off-by: Juergen Gross <jgross@xxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> diff --git a/drivers/net/xen-netback/common.h b/drivers/net/xen-netback/common.h index 4ef648f79993..e5f254500c1c 100644 --- a/drivers/net/xen-netback/common.h +++ b/drivers/net/xen-netback/common.h @@ -364,7 +364,7 @@ int xenvif_dealloc_kthread(void *data); irqreturn_t xenvif_ctrl_irq_fn(int irq, void *data); bool xenvif_have_rx_work(struct xenvif_queue *queue, bool test_kthread); -void xenvif_rx_queue_tail(struct xenvif_queue *queue, struct sk_buff *skb); +bool xenvif_rx_queue_tail(struct xenvif_queue *queue, struct sk_buff *skb); void xenvif_carrier_on(struct xenvif *vif); diff --git a/drivers/net/xen-netback/interface.c b/drivers/net/xen-netback/interface.c index 186694f6c260..b83777d4d35e 100644 --- a/drivers/net/xen-netback/interface.c +++ b/drivers/net/xen-netback/interface.c @@ -249,14 +249,16 @@ xenvif_start_xmit(struct sk_buff *skb, struct net_device *dev) if (vif->hash.alg == XEN_NETIF_CTRL_HASH_ALGORITHM_NONE) skb_clear_hash(skb); - xenvif_rx_queue_tail(queue, skb); + if (!xenvif_rx_queue_tail(queue, skb)) + goto drop; + xenvif_kick_thread(queue); return NETDEV_TX_OK; drop: vif->dev->stats.tx_dropped++; - dev_kfree_skb(skb); + dev_kfree_skb_any(skb); return NETDEV_TX_OK; } diff --git a/drivers/net/xen-netback/rx.c b/drivers/net/xen-netback/rx.c index 6964f8b1a36b..5067fa0c751f 100644 --- a/drivers/net/xen-netback/rx.c +++ b/drivers/net/xen-netback/rx.c @@ -82,9 +82,10 @@ static bool xenvif_rx_ring_slots_available(struct xenvif_queue *queue) return false; } -void xenvif_rx_queue_tail(struct xenvif_queue *queue, struct sk_buff *skb) +bool xenvif_rx_queue_tail(struct xenvif_queue *queue, struct sk_buff *skb) { unsigned long flags; + bool ret = true; spin_lock_irqsave(&queue->rx_queue.lock, flags); @@ -92,8 +93,7 @@ void xenvif_rx_queue_tail(struct xenvif_queue *queue, struct sk_buff *skb) struct net_device *dev = queue->vif->dev; netif_tx_stop_queue(netdev_get_tx_queue(dev, queue->id)); - kfree_skb(skb); - queue->vif->dev->stats.rx_dropped++; + ret = false; } else { if (skb_queue_empty(&queue->rx_queue)) xenvif_update_needed_slots(queue, skb); @@ -104,6 +104,8 @@ void xenvif_rx_queue_tail(struct xenvif_queue *queue, struct sk_buff *skb) } spin_unlock_irqrestore(&queue->rx_queue.lock, flags); + + return ret; } static struct sk_buff *xenvif_rx_dequeue(struct xenvif_queue *queue)