Commit ffb4d6c8 authored Sep 15, 2016 by Eric Dumazet Committed by David S. Miller Sep 17, 2016

tcp: fix overflow in __tcp_retransmit_skb()



If a TCP socket gets a large write queue, an overflow can happen
in a test in __tcp_retransmit_skb() preventing all retransmits.

The flow then stalls and resets after timeouts.

Tested:

sysctl -w net.core.wmem_max=1000000000
netperf -H dest -- -s 1000000000

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

parent cce94483

net/ipv4/tcp_output.c

+2 −1

Original line number	Diff line number	Diff line
		@@ -2605,7 +2605,8 @@ int __tcp_retransmit_skb(struct sock sk, struct sk_buff skb, int segs)
		* copying overhead: fragmentation, tunneling, mangling etc.
		*/
		if (atomic_read(&sk->sk_wmem_alloc) >
		min(sk->sk_wmem_queued + (sk->sk_wmem_queued >> 2), sk->sk_sndbuf))
		min_t(u32, sk->sk_wmem_queued + (sk->sk_wmem_queued >> 2),
		sk->sk_sndbuf))
		return -EAGAIN;

		if (skb_still_in_host_queue(sk, skb))

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