From patchwork Thu May 18 18:22:33 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Wei Wang X-Patchwork-Id: 764124 X-Patchwork-Delegate: davem@davemloft.net Return-Path: X-Original-To: patchwork-incoming@ozlabs.org Delivered-To: patchwork-incoming@ozlabs.org Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id 3wTKKt2HCNz9s7B for ; Fri, 19 May 2017 04:22:42 +1000 (AEST) Authentication-Results: ozlabs.org; dkim=pass (2048-bit key; unprotected) header.d=google.com header.i=@google.com header.b="bkXOx+Zt"; dkim-atps=neutral Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755434AbdERSWk (ORCPT ); Thu, 18 May 2017 14:22:40 -0400 Received: from mail-pf0-f178.google.com ([209.85.192.178]:33338 "EHLO mail-pf0-f178.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751704AbdERSWh (ORCPT ); Thu, 18 May 2017 14:22:37 -0400 Received: by mail-pf0-f178.google.com with SMTP id e193so27718270pfh.0 for ; Thu, 18 May 2017 11:22:37 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=from:to:cc:subject:date:message-id; bh=2hD0TOuK9y2WM8nEQVW2MluUr90RMlLUbU0r5iL1mvw=; b=bkXOx+ZtQhV7Rm4IJn1MIHSjHLNWT4xqxrDEM+lZ/KQVhZrSIvKODTtIlISz7up5g7 l2py2R0HcYbRuIQFLhltrsR8IqTIaMGRF7Wsvb2bZ99L/V3UZvwPPWqV9cbsKPiGb/KA 4zAwTmsO0H6IqygH+yDmhtYAItjh6xN1O3BTK58l3At/pT25O3jIKdzOH/1R+TH7PMLu h6kc6lFBqX0SZtSRaoaJyeB7hi3HbO3nR9DAQ/AesjoYWS+Mz++p85IMzoM6dFuYRuOr rIreveJNCHkiKgh15APZcnKBD4RUZw6E6rkwAVNsxBqXyOGXF8qK4WSfuTW9FYeJ8uay T4xg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id; bh=2hD0TOuK9y2WM8nEQVW2MluUr90RMlLUbU0r5iL1mvw=; b=rrpm0NX4VqY/2nGo1vzzv0+USgQf7WUF1OYeWLMymV9HKQrhbj4j1HS/wgmPUNNXbR tXxvTuovk7/uTF5+QpfsTh4R2iVPnUe1AqdVtIYkyoHPFV0DLxhfjiO9OtJBceXd43UN NZfr/IXlXzEdIGkuyrhVsqvOzpi0u5r+vk0KFFV/0XZNwz+ts4zf3jid6tT99hCh3Dxd I3YJerSB7y+CCY8Z+droKbDLewj8xATHrc3PcC9bvkQ3X+mhTNL82Pz5/2AN9m/bi2BO M9pyPk6KtnQmMzQbHq2cCPpubyk6GkxXs8a6imzOHHiqsRty3Mz0jswwe3e3doYhKUuo tcuA== X-Gm-Message-State: AODbwcCcJ8kyTddJj7c/dDPjYtmsbejYYvwUfXPA9QyvByXR+0EUufDc HjycidFllH+y9w35 X-Received: by 10.84.225.130 with SMTP id u2mr6334057plj.91.1495131757123; Thu, 18 May 2017 11:22:37 -0700 (PDT) Received: from localhost ([2620:15c:2cb:201:b12e:6427:edf1:dbb]) by smtp.gmail.com with ESMTPSA id r73sm10146385pfa.65.2017.05.18.11.22.36 (version=TLS1_2 cipher=AES128-SHA bits=128/128); Thu, 18 May 2017 11:22:36 -0700 (PDT) From: Wei Wang X-Google-Original-From: Wei Wang To: David Miller , netdev@vger.kernel.org Cc: Yuchung Cheng , Neal Cardwell , Eric Dumazet , Wei Wang Subject: [PATCH net] tcp: initialize rcv_mss to TCP_MIN_MSS instead of 0 Date: Thu, 18 May 2017 11:22:33 -0700 Message-Id: <20170518182233.100933-1-tracywwnj@gmail.com> X-Mailer: git-send-email 2.13.0.303.g4ebf302169-goog Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org From: Wei Wang When tcp_disconnect() is called, inet_csk_delack_init() sets icsk->icsk_ack.rcv_mss to 0. This could potentially cause tcp_recvmsg() => tcp_cleanup_rbuf() => __tcp_select_window() call path to have division by 0 issue. So this patch initializes rcv_mss to TCP_MIN_MSS instead of 0. Reported-by: Andrey Konovalov Signed-off-by: Wei Wang Signed-off-by: Eric Dumazet Signed-off-by: Neal Cardwell Signed-off-by: Yuchung Cheng --- net/ipv4/tcp.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c index 1e4c76d2b827..842b575f8fdd 100644 --- a/net/ipv4/tcp.c +++ b/net/ipv4/tcp.c @@ -2320,6 +2320,10 @@ int tcp_disconnect(struct sock *sk, int flags) tcp_set_ca_state(sk, TCP_CA_Open); tcp_clear_retrans(tp); inet_csk_delack_init(sk); + /* Initialize rcv_mss to TCP_MIN_MSS to avoid division by 0 + * issue in __tcp_select_window() + */ + icsk->icsk_ack.rcv_mss = TCP_MIN_MSS; tcp_init_send_head(sk); memset(&tp->rx_opt, 0, sizeof(tp->rx_opt)); __sk_dst_reset(sk);