[PATCH 4.19 15/49] xen/netback: dont call kfree_skb() with interrupts disabled

Greg Kroah-Hartman
2022-12-12T13:49:13Z

From: Juergen Gross <jgross@suse.com>

[ 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@huawei.com>
Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
Signed-off-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/net/xen-netback/common.h | 2 +-
drivers/net/xen-netback/interface.c | 6 ++++--
drivers/net/xen-netback/rx.c | 8 +++++---
3 files changed, 10 insertions(+), 6 deletions(-)

diff --git a/drivers/net/xen-netback/common.h b/drivers/net/xen-netback/common.h
index eeb8c575b758..92d30ebdb111 100644
--- a/drivers/net/xen-netback/common.h
+++ b/drivers/net/xen-netback/common.h
@@ -365,7 +365,7 @@ 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 a3629f22290d..df2027082763 100644
--- a/drivers/net/xen-netback/interface.c
+++ b/drivers/net/xen-netback/interface.c
@@ -255,14 +255,16 @@ 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 6f940a32dcb8..ab216970137c 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)
--
2.35.1