From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 36DEA19BAB for ; Wed, 7 Jun 2023 20:33:45 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id A722AC433D2; Wed, 7 Jun 2023 20:33:44 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1686170025; bh=p/Bh9a2dS7SHO1gHCuhPwIJPWyjXGAkK+aRZAG4qgO0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=D13sDstNjJqraTWmMlyG2k+/caERzrp0svxXqhiFUG7HsnwwXmjhMHUNM1OIBa2S9 t7z0XhPlY925+NXxoc2bmrA+hS0wUo5IWX+XoOiEQJFqmw+0zcUeQjx8Qn8+Uslvcx OTQkEpkawe8ZsqOxFc2+rvWL6c+/gSXIyJtxJ16A= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Jack Yang , Eric Dumazet , Cambda Zhu , Jason Xing , Jakub Kicinski , Sasha Levin Subject: [PATCH 4.19 17/88] tcp: Return user_mss for TCP_MAXSEG in CLOSE/LISTEN state if user_mss set Date: Wed, 7 Jun 2023 22:15:34 +0200 Message-ID: <20230607200859.182263930@linuxfoundation.org> X-Mailer: git-send-email 2.41.0 In-Reply-To: <20230607200854.030202132@linuxfoundation.org> References: <20230607200854.030202132@linuxfoundation.org> User-Agent: quilt/0.67 Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit From: Cambda Zhu [ Upstream commit 34dfde4ad87b84d21278a7e19d92b5b2c68e6c4d ] This patch replaces the tp->mss_cache check in getting TCP_MAXSEG with tp->rx_opt.user_mss check for CLOSE/LISTEN sock. Since tp->mss_cache is initialized with TCP_MSS_DEFAULT, checking if it's zero is probably a bug. With this change, getting TCP_MAXSEG before connecting will return default MSS normally, and return user_mss if user_mss is set. Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Reported-by: Jack Yang Suggested-by: Eric Dumazet Link: https://lore.kernel.org/netdev/CANn89i+3kL9pYtkxkwxwNMzvC_w3LNUum_2=3u+UyLBmGmifHA@mail.gmail.com/#t Signed-off-by: Cambda Zhu Link: https://lore.kernel.org/netdev/14D45862-36EA-4076-974C-EA67513C92F6@linux.alibaba.com/ Reviewed-by: Jason Xing Reviewed-by: Eric Dumazet Link: https://lore.kernel.org/r/20230527040317.68247-1-cambda@linux.alibaba.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin --- net/ipv4/tcp.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c index 22218ad71409f..cb96775fc86f6 100644 --- a/net/ipv4/tcp.c +++ b/net/ipv4/tcp.c @@ -3376,7 +3376,8 @@ static int do_tcp_getsockopt(struct sock *sk, int level, switch (optname) { case TCP_MAXSEG: val = tp->mss_cache; - if (!val && ((1 << sk->sk_state) & (TCPF_CLOSE | TCPF_LISTEN))) + if (tp->rx_opt.user_mss && + ((1 << sk->sk_state) & (TCPF_CLOSE | TCPF_LISTEN))) val = tp->rx_opt.user_mss; if (tp->repair) val = tp->rx_opt.mss_clamp; -- 2.39.2