From: Eric Dumazet Date: Thu, 15 Sep 2016 15:12:33 +0000 (-0700) Subject: tcp: fix overflow in __tcp_retransmit_skb() X-Git-Tag: v3.12.68~43 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=85974477c81193a33b3a757d007e8bbaf5bf0516;p=thirdparty%2Fkernel%2Fstable.git tcp: fix overflow in __tcp_retransmit_skb() [ Upstream commit ffb4d6c8508657824bcef68a36b2a0f9d8c09d10 ] 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 Signed-off-by: David S. Miller Signed-off-by: Jiri Slaby --- diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c index aa72c9d604a00..f08921156be86 100644 --- a/net/ipv4/tcp_output.c +++ b/net/ipv4/tcp_output.c @@ -2336,7 +2336,8 @@ int __tcp_retransmit_skb(struct sock *sk, struct sk_buff *skb) * 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 (before(TCP_SKB_CB(skb)->seq, tp->snd_una)) {