From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-yw1-f169.google.com (mail-yw1-f169.google.com [209.85.128.169]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 2DCFA2DCF74 for ; Wed, 30 Jul 2025 16:58:43 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.128.169 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1753894724; cv=none; b=EFB7NBTgxBqNpwTZ8KjDlhBhEasUyWrDkhfUghcnzJUi70acLdIZWjQeW6mYY37VhBOM4gtW6BscQp9uFu6zw5OtE0kljL8FK/YifrlwEUbBzNOo8BLKcsnqVaPexCTQn0TjWezmhhYbByr6Dr27RP4LZ1Ad8BS05+ZkyVxzIKY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1753894724; c=relaxed/simple; bh=54v3bzbw0nescITxi85iSTM3fxDNBHHqtZdwYKZ0fB0=; h=Date:From:To:Cc:Message-ID:In-Reply-To:References:Subject: Mime-Version:Content-Type; b=VPnfTM47bU11tV/Nzjv1l0jPFpw6cFQwwwPYjq2/E2F/UQFsBfGPGVtF4mEkFXxdKKSIIW4Tcv6PJF549n3vNEgMzLhve2RWOKBbg8sxpzBqCB4b2fW4f6ravI+Rmn3ykFrBcvtNcX9W1l1g6Bv1U4ms6w4wE9nGPPnV0CE1qOQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b=BsA40qPD; arc=none smtp.client-ip=209.85.128.169 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="BsA40qPD" Received: by mail-yw1-f169.google.com with SMTP id 00721157ae682-717b580ff2aso400487b3.0 for ; Wed, 30 Jul 2025 09:58:42 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1753894722; x=1754499522; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:subject:references :in-reply-to:message-id:cc:to:from:date:from:to:cc:subject:date :message-id:reply-to; bh=/IWxXiWmVPjESHDim+bjLIHEGiFk0DfaTgae+/iJVmM=; b=BsA40qPDuOFac354tcu8UqFZgVPrAahgYEzhNSRP5fYh+v1hcXJqpm5IS2bbM59M2D lOEfSBfDjDAGrn1k91y1fDUls+J7wxH8Z0gArFYPaM4AirOtnL/8AS7vtzDBiuJmCapw L51j25UmVKdjhkV34pke+J1boCJ1b9HBm/Ok+76qgLDyoXWq2PFUuFBcjaaYpfNM6yZc BXHiICFXuvaHVSUZHBWiiwNKyIE/s0ba1qTTkLOiHwakS7WRJGhNzMAQnXAaeroMkthu nNNwfjcmgwLYplvzHJpRFgp64C/kk6Ok+l0gE07mUu33qBVJg6ajMpNHhPwf5A5tgCDK bCfw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1753894722; x=1754499522; h=content-transfer-encoding:mime-version:subject:references :in-reply-to:message-id:cc:to:from:date:x-gm-message-state:from:to :cc:subject:date:message-id:reply-to; bh=/IWxXiWmVPjESHDim+bjLIHEGiFk0DfaTgae+/iJVmM=; b=FgXM63JSuM/jln3yuTo6FDwTYNYAOucMI+e20t/ctrzP3/uTvcO8yGK8DwFesjGycy 8krlzXO11HmbwuO6qTmH2uuDPc4BrfULgzGIcbYeiuMP+ZwS7XZ1+j4lpTCdUlcfafYv YX4A883GB7mL0MVccgsCV0Tm6Y1abzd0SmM602vyymXqv77Bme1064nmh1yCTv2zBjuo sTE/mg0NzbBNjVC4XbHUqGxVurVPJnpowxrGEQ6lCDca/0goPOhaDdE0jA4/85LyqaTc DMqLf87XMtafgGDQTlyN70lEamezEgBtozjasyIhH9MENjPcN3BGQQvZADkr07wbW5zK 9h/A== X-Forwarded-Encrypted: i=1; AJvYcCW6KP6na09bqWAt3DEpr7nUM8kT7cW0NpQL37nj+EBaC7XTU9WNyq9wg8pJ/lAf2RybjEj0Kp8=@vger.kernel.org X-Gm-Message-State: AOJu0YycyTBxJyVWEnek7qNMBtQvVoAri19Z+Uyk6HJu5bJFR0t0tmGN olr6U9c4ofaB2xQQWzW5OZpvao2UNtYz26zrTmpw9MFdZ7tswJuFhSsT X-Gm-Gg: ASbGnctfbtQ8ianD3UAOLOvjtfwjS282lXMdahu00swL1HviXLYsRvFLC5PL5AOJ6Vb XnYX66Tl42IFaeliLgbfEGu7vNGdK2lnzwAM8eJbiQY+QJqscHV+zQee6mcbRGCpm7IZb4uZ13H DNR304d+dIqsfaho94dnqsTPhIdVh50e1Xhr519o+5Sci7lweYhw5F7ST2+bBUP/jji5sORKwTs wM6ibDnYKG3c2bUbVbVClQc+2wD4oaUHiT9Lz+7pfdiC/wGzStJP1xXh237W2yz6p3XhVnKLJEt Dsbr2P7cwntjFqCEBnwd3wfnEu9IhCIjc6va2Y8f4gAWw81Aq3cJKDvzpaz0daVOUq0wBPp+ZQG 3LgAufCA7ru3rJWGmYl2C+tZU6S9Oa4PFtoHuzC/a0iRY4FzMmvDPgjVHN32ilqYag9Utzw== X-Google-Smtp-Source: AGHT+IG1esaa0jeRYIopiwYvyW8UvJHiwMI3Wms5uLs9CjY4OldOKNvvUVoPC11/K6WavbQA6s6kXw== X-Received: by 2002:a05:690c:6909:b0:71a:2d5f:49d0 with SMTP id 00721157ae682-71a465215aamr56873757b3.1.1753894722082; Wed, 30 Jul 2025 09:58:42 -0700 (PDT) Received: from localhost (23.67.48.34.bc.googleusercontent.com. [34.48.67.23]) by smtp.gmail.com with UTF8SMTPSA id 00721157ae682-719f23e89e6sm24779957b3.85.2025.07.30.09.58.40 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 30 Jul 2025 09:58:40 -0700 (PDT) Date: Wed, 30 Jul 2025 12:58:39 -0400 From: Willem de Bruijn To: Eric Dumazet , "David S . Miller" , Jakub Kicinski , Paolo Abeni Cc: Simon Horman , Willem de Bruijn , David Ahern , netdev@vger.kernel.org, eric.dumazet@gmail.com, Eric Dumazet , syzbot+af43e647fd835acc02df@syzkaller.appspotmail.com Message-ID: <688a4f3f7d969_1d29db294cf@willemb.c.googlers.com.notmuch> In-Reply-To: <20250730131738.3385939-1-edumazet@google.com> References: <20250730131738.3385939-1-edumazet@google.com> Subject: Re: [PATCH net] ipv6: reject malicious packets in ipv6_gso_segment() Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Eric Dumazet wrote: > syzbot was able to craft a packet with very long IPv6 extension headers > leading to an overflow of skb->transport_header. > > This 16bit field has a limited range. > > Add skb_reset_transport_header_careful() helper and use it > from ipv6_gso_segment() > > WARNING: CPU: 0 PID: 5871 at ./include/linux/skbuff.h:3032 skb_reset_transport_header include/linux/skbuff.h:3032 [inline] > WARNING: CPU: 0 PID: 5871 at ./include/linux/skbuff.h:3032 ipv6_gso_segment+0x15e2/0x21e0 net/ipv6/ip6_offload.c:151 > Modules linked in: > CPU: 0 UID: 0 PID: 5871 Comm: syz-executor211 Not tainted 6.16.0-rc6-syzkaller-g7abc678e3084 #0 PREEMPT(full) > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025 > RIP: 0010:skb_reset_transport_header include/linux/skbuff.h:3032 [inline] > RIP: 0010:ipv6_gso_segment+0x15e2/0x21e0 net/ipv6/ip6_offload.c:151 > Call Trace: > > skb_mac_gso_segment+0x31c/0x640 net/core/gso.c:53 > nsh_gso_segment+0x54a/0xe10 net/nsh/nsh.c:110 > skb_mac_gso_segment+0x31c/0x640 net/core/gso.c:53 > __skb_gso_segment+0x342/0x510 net/core/gso.c:124 > skb_gso_segment include/net/gso.h:83 [inline] > validate_xmit_skb+0x857/0x11b0 net/core/dev.c:3950 > validate_xmit_skb_list+0x84/0x120 net/core/dev.c:4000 > sch_direct_xmit+0xd3/0x4b0 net/sched/sch_generic.c:329 > __dev_xmit_skb net/core/dev.c:4102 [inline] > __dev_queue_xmit+0x17b6/0x3a70 net/core/dev.c:4679 > > Fixes: d1da932ed4ec ("ipv6: Separate ipv6 offload support") > Reported-by: syzbot+af43e647fd835acc02df@syzkaller.appspotmail.com > Closes: https://lore.kernel.org/netdev/688a1a05.050a0220.5d226.0008.GAE@google.com/T/#u > Signed-off-by: Eric Dumazet Reviewed-by: Willem de Bruijn