From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-wr1-f51.google.com (mail-wr1-f51.google.com [209.85.221.51]) (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 B37D739FCC4 for ; Tue, 21 Apr 2026 08:54:22 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.221.51 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776761664; cv=none; b=TQz7UxMtTlU613NV9XnERE7tHTf5SB151aSWdOYPTtf8QghMzynfibwu/xVZhryTHEzu9UES/MdhbleSJ3abfCZcDMkuoK2F2SEv3aYwmp30NGQR2Ez6ij1M3e/xGiVtvtslCbzdFJdxEQr3Xgv0/mHc36KZVnrPCN4Ffj9WTb0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776761664; c=relaxed/simple; bh=dU+9BdjF0sSpHUJiYDtB2Gktv8KhihkDTc5ZL19RUS4=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=qTRP1ESQC6QaRLyx6FlTe+Y+2cjOCzXl7vHr/T0Lp0HxZNf5rfPdZpLKYaF3nu2DOUlSWOLh51Q8cxARoi2piTyIrjXn0V1pLiAVtM6NzTLsVRwp5Npnm3wdC5RfVy/l77Jk+qqX2S1viwlyF58xg6vxof0fGS35hiMSrEoFnMk= 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=pQmB7H9P; arc=none smtp.client-ip=209.85.221.51 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="pQmB7H9P" Received: by mail-wr1-f51.google.com with SMTP id ffacd0b85a97d-43d64313c39so3101379f8f.3 for ; Tue, 21 Apr 2026 01:54:22 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20251104; t=1776761661; x=1777366461; darn=vger.kernel.org; h=content-transfer-encoding:in-reply-to:from:content-language :references:cc:to:subject:user-agent:mime-version:date:message-id :from:to:cc:subject:date:message-id:reply-to; bh=dU+9BdjF0sSpHUJiYDtB2Gktv8KhihkDTc5ZL19RUS4=; b=pQmB7H9PSuVCeV4gvVpOUYrI8dfQSrQXvkgXB94m8YT/mrqlLvy9G1UeC4SKORnoVx 0Xdg+wlggpl+9vxIg+pTOYaN0t8MXTHj4xwJnwTMhf0Mc+tWU9mcTWjTk3p71IWJr5Vk M57UvSSo1OBhV+Qsfqhi6vuaFAylrnYMLjbItZaNe+c9jLmCaz2r9im3BLO24xNYy+BZ I9qPLWYfwnomtCXhTfenvaqFeiChZ05+2c9Kok5NP5Dfq2woAqLb8Uu8jla5Qj3FZ2Q/ xwBdDBexooAf8I6Ns9kTnTt+iUgifxZNEm5qxxnpPt1c9Fn11255eVRip3RuOQfH2D8q j4IQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1776761661; x=1777366461; h=content-transfer-encoding:in-reply-to:from:content-language :references:cc:to:subject:user-agent:mime-version:date:message-id :x-gm-gg:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=dU+9BdjF0sSpHUJiYDtB2Gktv8KhihkDTc5ZL19RUS4=; b=JTJWRSb0au8O0mDXvbOa4SHNprdSNpwA83dpO4Ioh0Sq+jMCKOXdboYrBG+IiML7KT LefDz/3AflYgvNAnY8wQvxS01NGA24KFNWhHpW+aYap7rClC6oKIvnDmdpAMe+mxFHH+ xwG0amFj+rTYTgREVknNwWTbF9NGO82OLBz0ClIs1roy1HgqdAaePnv//M1uA3zUOKiP z1wu0XwtNcXyAewJIdiG8Pc2rC6HhtHdYCgJBhZObQ3SQ2i5LxWJy3XBxB0xxHXFxt/i eFkNSetL65t9FHI0sR1eo90fRvD8e18zHkL5mR3cSI5Nep1yoUN6Uzt66fuyboFz7t60 n7mA== X-Forwarded-Encrypted: i=1; AFNElJ+VawpltGt881WWES9FguNrflQIfm6iy4WqKVI6pICBBLOe0bMaVChkF80VbRDcjXKHoatBpvg=@vger.kernel.org X-Gm-Message-State: AOJu0YwJiyOw4L6ORnoaHfoO8SRUS3fMWnfRzitVu2cJULha1SY57v7z hVQjcUj7UinIgmnL96p892ZCZpeMKDcECj2n/NM1QI4cSSKWgv3sXjnx X-Gm-Gg: AeBDievxslLE95boH/wRhL+17Vo4Q2uh77z6hhfpjkQ6m+59xrQ9r02dqrfSGgcMof5 ZbGS6cQFmYbuRTowEL+/z6rA5eCwR6ocq5CnJwKp21N1Ukzl1akhLRvqIGI0oXKitlbATfVyJUW Il7Y5iNcu/48gDewSsusPqMS+9QqMO/SFbhthrAnUUTA9utE3J/YqwmHhtOAGRrQ9/yZwDwcX1W 6tDZ7Q3Ww+YR3BUTPshBk9SsSbxslduQw/RMqRLEGMqlb7Fx1rb5IPbqA+OdveO40Enp1qT6P4B kQajgvh/AAVIctmOn2Aa1L+WGYqGycn8CCYuSw7/MyPo66ay1akjr/wTGwd+hilIuBRYKVoq9xq 7ssXErow7UAH1QnhTvTwRfeYICYp4haJ3b0vFi7GfhBLBkg9g9zv6S2WceesyJT0MkTwfSNzHBC k9QMgsYvOKvXPhAtL+HORngGfg7uUy5gNYn8yo X-Received: by 2002:a05:6000:24c7:b0:43d:740:fb37 with SMTP id ffacd0b85a97d-43fe3dfbe4emr25790843f8f.24.1776761660781; Tue, 21 Apr 2026 01:54:20 -0700 (PDT) Received: from [192.168.1.169] ([46.10.223.24]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-43fe4cb1249sm32516285f8f.5.2026.04.21.01.54.19 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 21 Apr 2026 01:54:20 -0700 (PDT) Message-ID: <9ce273bd-6912-4442-8672-4c89bebf32ed@gmail.com> Date: Tue, 21 Apr 2026 11:54:19 +0300 Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH net] netdevsim: Initialize all fields of ip header when building dummy sk_buff To: Breno Leitao Cc: kuba@kernel.org, andrew+netdev@lunn.ch, davem@davemloft.net, edumazet@google.com, pabeni@redhat.com, netdev@vger.kernel.org, linux-kernel@vger.kernel.org References: <20260421073738.22110-1-zlatistiv@gmail.com> Content-Language: en-US From: "Nikola Z. Ivanov" In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 4/21/26 11:19 AM, Breno Leitao wrote: > On Tue, Apr 21, 2026 at 10:37:38AM +0300, Nikola Z. Ivanov wrote: >> Syzbot reports a KMSAN uninit-value originating from >> nsim_dev_trap_skb_build, with the allocation also >> being performed in the same function. >> >> The cause of the KMSAN warning is a missing assignment of >> the tos and id fields of the ip header. >> >> Fix this by calling skb_put_zero instead of skb_put to >> guarantee null initialization. >> Additionally remove the now redundant zero assignments >> and reorder the remaining ones so that they more closely >> match the order of the fields as they appear in the ip header. >> >> Closes: https://syzkaller.appspot.com/bug?extid=23d7fcd204e3837866ff > How do you check in the report above that the missig un-initialized > fields are "tos" and "id"? > > Thanks for the fix, > --breno Hi Breno, I don't think it is visible here, my guess would be because the checksum calculator walks the header in small chunks instead of referencing its fields. The whole "KMSAN: uninit-value in irqentry_exit_to_kernel_mode_preempt" doesn't really sound quite right. Thank you!