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ping: Fix race in free in receive path
An exception is seen in ICMP ping receive path where the skb destructor sock_rfree() tries to access a freed socket. This happens because ping_rcv() releases socket reference with sock_put() and this internally frees up the socket. Later icmp_rcv() will try to free the skb and as part of this, skb destructor is called and which leads to a kernel panic as the socket is freed already in ping_rcv(). -->|exception -007|sk_mem_uncharge -007|sock_rfree -008|skb_release_head_state -009|skb_release_all -009|__kfree_skb -010|kfree_skb -011|icmp_rcv -012|ip_local_deliver_finish Fix this incorrect free by cloning this skb and processing this cloned skb instead. This patch was suggested by Eric Dumazet Signed-off-by: Subash Abhinov Kasiviswanathan <subashab@codeaurora.org> Cc: Eric Dumazet <edumazet@google.com> Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
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1 changed files with 4 additions and 1 deletions
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@ -966,8 +966,11 @@ bool ping_rcv(struct sk_buff *skb)
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sk = ping_lookup(net, skb, ntohs(icmph->un.echo.id));
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if (sk != NULL) {
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struct sk_buff *skb2 = skb_clone(skb, GFP_ATOMIC);
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pr_debug("rcv on socket %p\n", sk);
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ping_queue_rcv_skb(sk, skb_get(skb));
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if (skb2)
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ping_queue_rcv_skb(sk, skb2);
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sock_put(sk);
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return true;
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}
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