From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1793831147; b=TQIhK75k4tQO8M97wiXmUvtFh6ImjqC/CGOcCbeuVzJHUpOUfpooAlTrz59qCo8JeBsg r6tAWpUpfUAHYlySU+/TdxPekyj7Q7oy3psBim1xFAygLKOSNLi0VaSGN8kOduN48RHFZ TiSrA7LugABrAKFw1vN4x/ob5WzmxXVFwMlO0ULXOSebX7U6tO6cfV0BR5qIgOto8Zfg4 qNI95J5bp/UeK9YJ4n/lARnfuarKrxw8v3MVqAsZnsEX3o+yw5zI0/GJd1TKfxaRzn71k x6CzTSNF8TKdJSAqJK6jHK2NvPP6GMI4jDIrzDo79/BQftAiqJ2O7tBvKqN1aR7Qm2g== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793831147; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: In-Reply-To:References:User-Agent:X-stable:X-Patchwork-Hint: MIME-Version:Content-Transfer-Encoding; bh=06/ZEW1TXaUX6NTltHcTBv0nEB8xZZ5KTdI4GdQpLXI=; b=GJ7fZZYKe8nnrHVQuHndRORGGaOP2LAMOSN1BRW2oRNp2VkvW8YbsUMEeN8MWGgVZtFj l7wb30PqnCYZgWD75VnaGFOLPz5QHbArIGsU+oNP2c3Zj2Tgf0evlgzryNS3Qs3+P0lNa Zq80FnURfTqmM4H/EFQJo3ypF3KY2AHEOq7TLBtQjbf3EKP1FSZYU4vNFNqPgMdDbd9JK lxC/kX+2+nMMCc2Ptp0F0zCGzdi7bJ1BE47s2NYg6wkzxaRkogr9V+guiKeQ1ZS5KuHMl TgXyVrUzD6yUBaqsZ1Ic53BEcxXSXazVKonszOT3lz5qhBKs8MW1CHduC08+v8ybFig== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=linuxfoundation.org header.i=@linuxfoundation.org header.a=rsa-sha256 header.s=korg header.b=b48WpdIf; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 8BBB9606B3B8; Wed, 4 Nov 2026 22:25:47 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key, unprotected) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.a=rsa-sha256 header.s=korg header.b=b48WpdIf Received: by smtp.kernel.org (Postfix) with ESMTPSA id 224231F000C1; Wed, 4 Nov 2026 22:25:47 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1793831147; bh=06/ZEW1TXaUX6NTltHcTBv0nEB8xZZ5KTdI4GdQpLXI=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=b48WpdIfrVF+IW1RF2p9RQRZNiYytS+22+GUWseKovs9hAUQKU5LEpe02PCPNrrlb O8PpqTFABTIza1mRiZWiI0StYL+c0+Zesfb+fesTH4aLO7pHvM8nXMv41c69CKaDUE WLuinKvqtUPXEbncVmTuRmtANIi+m8v5aUI+C98E= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Eric Dumazet , co+71b6509cb791e531@bugs.sh, Kaho Jiang , Paolo Abeni Subject: [PATCH 6.18 0526/1005] net: ipv4: add zero check for snd_cwnd_clamp Date: Wed, 4 Nov 2026 16:04:19 -0500 Message-ID: <20261104211058.648972294@linuxfoundation.org> X-Mailer: git-send-email 2.56.0 In-Reply-To: <20261104211043.516122098@linuxfoundation.org> References: <20261104211043.516122098@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore X-Mailing-List: patches@lists.linux.dev List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Kaho Jiang commit 363c8c79220d0db4d65dcd570529ddda15067cb5 upstream. When RTAX_CWND is locked, user is able to pass 0 into it. This could lead to writing 0 to tp->snd_cwnd, leading to a division by zero error. Oops: divide error: 0000 [#1] SMP KASAN NOPTI Call Trace: tcp_reno_cong_avoid (net/ipv4/tcp_cong.c:510 (discriminator 1)) tcp_ack (net/ipv4/tcp_input.c:3517 net/ipv4/tcp_input.c:3873 net/ipv4/tcp_input.c:4440) tcp_rcv_established (net/ipv4/tcp_input.c:6685) tcp_v4_do_rcv (net/ipv4/tcp_ipv4.c:1854) tcp_v4_rcv (net/ipv4/tcp_ipv4.c:2248) ip_protocol_deliver_rcu (net/ipv4/ip_input.c:207 (discriminator 1)) ip_local_deliver_finish (net/ipv4/ip_input.c:241 (discriminator 1)) ip_local_deliver (./include/linux/netfilter.h:325 ./include/linux/netfilter.h:319 net/ipv4/ip_input.c:262) ip_rcv (./include/net/dst.h:481 (discriminator 6) net/ipv4/ip_input.c:492 (discriminator 6) ./include/linux/netfilter.h:325 (discriminator 6) ./include/li) __netif_receive_skb_one_core (net/core/dev.c:6297 (discriminator 4)) __netif_receive_skb (net/core/dev.c:6410) process_backlog (net/core/dev.c:6761) __napi_poll.constprop.0 (net/core/dev.c:7830) net_rx_action (net/core/dev.c:7893 net/core/dev.c:8050) handle_softirqs (kernel/softirq.c:645) __irq_exit_rcu (kernel/softirq.c:679 kernel/softirq.c:519 kernel/softirq.c:758) irq_exit_rcu (kernel/softirq.c:775) sysvec_apic_timer_interrupt (arch/x86/kernel/apic/apic.c:1062 (discriminator 35) arch/x86/kernel/apic/apic.c:1062 (discriminator 35)) RIP: 0010:tcp_cong_avoid_ai (net/ipv4/tcp_cong.c:482) Fix by checking if user pass in zero as parameter and if lock is present. Fixes: 814d488c6126 ("tcp: fix the timid additive increase on stretch ACKs") Cc: stable@vger.kernel.org Suggested-by: Eric Dumazet Reported-by: co+71b6509cb791e531@bugs.sh Signed-off-by: Kaho Jiang Reviewed-by: Eric Dumazet Link: https://patch.msgid.link/20261021235732.1313305-2-kj2864@nyu.edu Signed-off-by: Paolo Abeni Signed-off-by: Greg Kroah-Hartman --- net/ipv4/metrics.c | 5 +++++ 1 file changed, 5 insertions(+) --- a/net/ipv4/metrics.c +++ b/net/ipv4/metrics.c @@ -60,6 +60,11 @@ static int ip_metrics_convert(struct nla if (ecn_ca) metrics[RTAX_FEATURES - 1] |= DST_FEATURE_ECN_CA; + if ((metrics[RTAX_LOCK - 1] & (1 << RTAX_CWND)) && !metrics[RTAX_CWND - 1]) { + NL_SET_ERR_MSG(extack, "Locked cwnd metric must be non zero"); + return -EINVAL; + } + return 0; }