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Re: [PATCH] net: Fix potential NULL pointer dereference in __skb_try_recv_datagram

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Jacob Siverskog <jacob@teenage.engineering> writes:
> This should fix a NULL pointer dereference I encountered (dump
> below). Since __skb_unlink is called while walking,
> skb_queue_walk_safe should be used.

The code in question is:

skb_queue_walk(queue, skb) {
	*last = skb;
	*peeked = skb->peeked;
	if (flags & MSG_PEEK) {
		if (_off >= skb->len && (skb->len || _off ||
					 skb->peeked)) {
			_off -= skb->len;
			continue;
		}

		skb = skb_set_peeked(skb);
		error = PTR_ERR(skb);
		if (IS_ERR(skb)) {
			spin_unlock_irqrestore(&queue->lock,
					       cpu_flags);
			goto no_packet;
		}
                
		atomic_inc(&skb->users);
	}  else
		__skb_unlink(skb, queue);

	spin_unlock_irqrestore(&queue->lock, cpu_flags);
	*off = _off;
	return skb;
}

__skb_unlink is only called prior to returning from the function.
Consequently, it won't affect the skb_queue_walk code.
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[PATCH] net: Fix potential NULL pointer dereference in __skb_try_recv_datagram Jacob Siverskog <jacob@teenage.engineering> - 2015-12-29 20:20 +0100
  Re: [PATCH] net: Fix potential NULL pointer dereference in __skb_try_recv_datagram Rainer Weikusat <rweikusat@mobileactivedefense.com> - 2015-12-29 20:50 +0100
    Re: [PATCH] net: Fix potential NULL pointer dereference in  __skb_try_recv_datagram David Miller <davem@davemloft.net> - 2015-12-29 21:10 +0100
      Re: [PATCH] net: Fix potential NULL pointer dereference in __skb_try_recv_datagram Jacob Siverskog <jacob@teenage.engineering> - 2015-12-30 12:20 +0100
        Re: [PATCH] net: Fix potential NULL pointer dereference in __skb_try_recv_datagram Eric Dumazet <edumazet@google.com> - 2015-12-30 14:30 +0100
          Re: [PATCH] net: Fix potential NULL pointer dereference in __skb_try_recv_datagram Eric Dumazet <edumazet@google.com> - 2015-12-30 15:40 +0100
          Re: [PATCH] net: Fix potential NULL pointer dereference in __skb_try_recv_datagram Jacob Siverskog <jacob@teenage.engineering> - 2015-12-30 15:40 +0100
            Re: [PATCH] net: Fix potential NULL pointer dereference in __skb_try_recv_datagram Cong Wang <xiyou.wangcong@gmail.com> - 2015-12-30 23:40 +0100
        Re: [PATCH] net: Fix potential NULL pointer dereference in __skb_try_recv_datagram Rainer Weikusat <rweikusat@mobileactivedefense.com> - 2015-12-30 16:40 +0100

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