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 71BA62868AF; Tue, 12 Aug 2025 17:51:35 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1755021095; cv=none; b=YGh2CyffOPQAR2bYSlgErjqUWWBtTKFldoEpkM3Ri9+aCAROlhrDERsd1oSodwCVUjOuQ+09LkBFP9GFxpKxRam+jm1KS0lqA0xSuoR6y3fYHVClPLDO8v8N4GiBRkXF5UEoNbooP5x1WlOwb1EJKaGvAjRYqkW1BCbJeuaE9EY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1755021095; c=relaxed/simple; bh=98wHyz+mvFXTOm+I+3lbO4eOY5Y1hlklNMCVR0/LQH0=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=LGDkfVKsEXdMHmq3Mol/VBRpcGklnE9AW9+p5ueNT4VF7C464yamoc25Iq860AR1QZpEI90jBholOB8Eqzrk/fImBRx2dEf2rusl492zrly7r7bXfsX9Ag8sNR9XL2dWGCYaVjErNeRwEeRFjDBYj0xlCDEyY9HKj0TshizWXSY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=TooewLlf; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="TooewLlf" Received: by smtp.kernel.org (Postfix) with ESMTPSA id F085CC4CEF1; Tue, 12 Aug 2025 17:51:34 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1755021095; bh=98wHyz+mvFXTOm+I+3lbO4eOY5Y1hlklNMCVR0/LQH0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=TooewLlfe1/muk3BkEkhM5jpIe4bimIF7Z+Dj4XjZk2I83KLXzfZTsq7adEwXSlEf vds4xJ/ihk4kIgapO6MECY7C4BJf97lNldm8Cst3/AqZDh6eZMENCTDGVOkTG9Rjdn VLAUWzi6LTQRuSsrFIuTIG5/P0bjq1uupuH4J18k= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, "xin.guo" , Eric Dumazet , Jakub Kicinski , Sasha Levin Subject: [PATCH 6.6 061/262] tcp: fix tcp_ofo_queue() to avoid including too much DUP SACK range Date: Tue, 12 Aug 2025 19:27:29 +0200 Message-ID: <20250812172955.586844297@linuxfoundation.org> X-Mailer: git-send-email 2.50.1 In-Reply-To: <20250812172952.959106058@linuxfoundation.org> References: <20250812172952.959106058@linuxfoundation.org> User-Agent: quilt/0.68 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.6-stable review patch. If anyone has any objections, please let me know. ------------------ From: xin.guo [ Upstream commit a041f70e573e185d5d5fdbba53f0db2fbe7257ad ] If the new coming segment covers more than one skbs in the ofo queue, and which seq is equal to rcv_nxt, then the sequence range that is duplicated will be sent as DUP SACK, the detail as below, in step6, the {501,2001} range is clearly including too much DUP SACK range, in violation of RFC 2883 rules. 1. client > server: Flags [.], seq 501:1001, ack 1325288529, win 20000, length 500 2. server > client: Flags [.], ack 1, [nop,nop,sack 1 {501:1001}], length 0 3. client > server: Flags [.], seq 1501:2001, ack 1325288529, win 20000, length 500 4. server > client: Flags [.], ack 1, [nop,nop,sack 2 {1501:2001} {501:1001}], length 0 5. client > server: Flags [.], seq 1:2001, ack 1325288529, win 20000, length 2000 6. server > client: Flags [.], ack 2001, [nop,nop,sack 1 {501:2001}], length 0 After this fix, the final ACK is as below: 6. server > client: Flags [.], ack 2001, options [nop,nop,sack 1 {501:1001}], length 0 [edumazet] added a new packetdrill test in the following patch. Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Signed-off-by: xin.guo Signed-off-by: Eric Dumazet Link: https://patch.msgid.link/20250626123420.1933835-2-edumazet@google.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin --- net/ipv4/tcp_input.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c index f7b95bc8ad60..8520c43726e2 100644 --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -4872,8 +4872,9 @@ static void tcp_ofo_queue(struct sock *sk) if (before(TCP_SKB_CB(skb)->seq, dsack_high)) { __u32 dsack = dsack_high; + if (before(TCP_SKB_CB(skb)->end_seq, dsack_high)) - dsack_high = TCP_SKB_CB(skb)->end_seq; + dsack = TCP_SKB_CB(skb)->end_seq; tcp_dsack_extend(sk, TCP_SKB_CB(skb)->seq, dsack); } p = rb_next(p); -- 2.39.5