[PATCH net] sock: sock_dequeue_err_skb() needs hard irq safety

[PATCH net] sock: sock_dequeue_err_skb() needs hard irq safety

[Eric Dumazet]

From: Eric Dumazet <edumazet@google.com>

Non NAPI drivers can call skb_tstamp_tx() and then sock_queue_err_skb()
from hard IRQ context.

Therefore, sock_dequeue_err_skb() needs to block hard irq or
corruptions or hangs can happen.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Fixes: 364a9e93243d1 ("sock: deduplicate errqueue dequeue")
Fixes: cb820f8e4b7f7 ("net: Provide a generic socket error queue delivery method for Tx time stamps.")
---
 net/core/skbuff.c |    5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index 88c613eab142..f80507823531 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -3621,13 +3621,14 @@ struct sk_buff *sock_dequeue_err_skb(struct sock *sk)
 {
 	struct sk_buff_head *q = &sk->sk_error_queue;
 	struct sk_buff *skb, *skb_next;
+	unsigned long flags;
 	int err = 0;
 
-	spin_lock_bh(&q->lock);
+	spin_lock_irqsave(&q->lock, flags);
 	skb = __skb_dequeue(q);
 	if (skb && (skb_next = skb_peek(q)))
 		err = SKB_EXT_ERR(skb_next)->ee.ee_errno;
-	spin_unlock_bh(&q->lock);
+	spin_unlock_irqrestore(&q->lock, flags);
 
 	sk->sk_err = err;
 	if (err)

Re: [PATCH net] sock: sock_dequeue_err_skb() needs hard irq safety

[David Miller]

From: Eric Dumazet <eric.dumazet@gmail.com>
Date: Wed, 18 Feb 2015 05:47:55 -0800

> From: Eric Dumazet <edumazet@google.com>
> 
> Non NAPI drivers can call skb_tstamp_tx() and then sock_queue_err_skb()
> from hard IRQ context.
> 
> Therefore, sock_dequeue_err_skb() needs to block hard irq or
> corruptions or hangs can happen.
> 
> Signed-off-by: Eric Dumazet <edumazet@google.com>
> Fixes: 364a9e93243d1 ("sock: deduplicate errqueue dequeue")
> Fixes: cb820f8e4b7f7 ("net: Provide a generic socket error queue delivery method for Tx time stamps.")

Applied and queued up for -stable, thanks Eric.