From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pj1-f41.google.com (mail-pj1-f41.google.com [209.85.216.41]) (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 98C4F3112B2 for ; Tue, 7 Jul 2026 14:47:35 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.216.41 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783435657; cv=none; b=OzBGvBvw1ceNF2SM6PztSHEz0xucQ/USiHxHflrD5l3gtE3LmpphfYucHmx/8W86hBS4T4p70PHRY0aCZr/6m0UcarfFJZlLvX76OBzHMGKRMKB/jlXN0qCuvN4nJFe7IwFpHq3zGuxRFGY7DT3g5Nr6sb+XOa+1OGWaNAP9oTs= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783435657; c=relaxed/simple; bh=PNv9zdSBVU59fmU9/7lEi5eHPqc+E/VlzTgKu/fSaII=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=lSoH4q9pJXzummkW+dshOQO5UufXSq80+KZvMqxB99PyAaqNdE1i706aqWjWII4TNnBIA5PawjF6ggmyMaR/30pi242RjXBpIUwNTdNPdin0jqtFNZof01Af4Tao6V8fDgz8rj7gtsvXaoGIgIRAe+v9PSID9R92lPPNQEnCUb0= 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=Q/IAw+ZW; arc=none smtp.client-ip=209.85.216.41 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="Q/IAw+ZW" Received: by mail-pj1-f41.google.com with SMTP id 98e67ed59e1d1-381b831d535so4877324a91.0 for ; Tue, 07 Jul 2026 07:47:35 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20251104; t=1783435655; x=1784040455; darn=vger.kernel.org; h=in-reply-to:content-disposition:content-type:mime-version :references:message-id:subject:cc:to:from:date:from:to:cc:subject :date:message-id:reply-to:content-type; bh=3aTkXAIBSsu3lXmX/xa/IfupA1waQVd+Dz2CaONflns=; b=Q/IAw+ZWgCHVf5meSUufA7niqEEkVq+BlEdLKGGCRLNTJ4JQvhbGdZifl6P4DgPVFe Q19RrYpKj3aNyEdtxlb+ouafq9sg28YC8JZGTUJbVZGjfsog73SmSI59avEcWj6bSOZJ aHIyvdy48Xi8QZBfaaz/ZHVyGmdMWR++7MFdwAIJ8gvxc50I5bd9FloJmFpMAhPKd7+q SnJk8Gmz8pGWrUc7Jhi0Rod+Jq7wSWvGFfIHT8mukBmFOA7h26o6kUXcSUVxY1epoimU 5IQTEDUEBYd/sMQ12apPAEk87pmwWrxeiaZ8P7/LQtU7ayY2gxdm4VVkZDmOfmo9ZnJ4 QczQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1783435655; x=1784040455; h=in-reply-to:content-disposition:content-type:mime-version :references:message-id:subject:cc:to:from:date:x-gm-gg :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to :content-type; bh=3aTkXAIBSsu3lXmX/xa/IfupA1waQVd+Dz2CaONflns=; b=DNpNA5RZs3k6PvzdT2PUDEAzsqIkwiSqrpCWIiAIxEpt9PwVg8ubiYOrWMj29lVcgm KBEhVYil0prEa83c0iemfgfq51c4uSIu3ksRPK2ikvmi/avBRshmDdWytgtDoQVYubiW eBvki2StryhpdXkl8bScIWnon9nkPfYyJlpnC3ZptkUztL/REfiJWHDrQyglPf63bFIM TQpD4ZsyfFo6WpqBMgJ8KgjG8aR2m9EF11la8AdP9DMOQLq1niMStY3e1aTLv+Td0kGr od6T+hldr+g997h6E6aAKayCygGDgA9lpBSvxj1fv7h8nDF3ol/h22Yfcdg3cM4feo9Q z/Ow== X-Gm-Message-State: AOJu0YymdExNfqOYS/AV+u/WKELx1X74RbCoE1kmO6wT/VxYwhNK/Ona eJVmWTQzcr0FdEmQxeLlUragkUMpBFfaT8hdfDcxzDURQ8LheoxS1OPDsnz5mQ== X-Gm-Gg: AfdE7cnn6hGfmYs2RnP0yYJquMwijX24hLD5DcPGhMyJxnTTx+ussySCMZEdK2eAqgj Mlxkt1mFWqd1w+p5Vr+ufdDLYhpHa87sb3FnVD4kXy6377KNkiLJBPz6x4lf4xibGwauUThkfxn K+y8IGOKF/SJE1gx4G/tc2DWl4O/p3yzmzahFQjjbtJej2zwgpH64vJVMagOHgRdynDjDkvhZpQ ecq28Mj1KXwcgWwEFbxCaqr0a/h5mhNE5ws75aTimO4zCMroFUO5vCs4n/iQFv+vWfco8ccw1fn YjtKeYuVQRsv/9UePlK8uPr4DXbxBO47cWkZ4I++MB+/Y6Rjvg87Yakc1+7nCRYiNduAe8jPPjE sqllEhrOCoeNh8vAuF4F873Uv/G8ILVvMMeUkeLAf0qNhPHMxC1fOk92ByAOhy10Ef6e9E+Nuuk QbXRZ2qIzkLQ== X-Received: by 2002:a17:90b:562c:b0:37e:144d:7f6e with SMTP id 98e67ed59e1d1-3875650bd7cmr5588414a91.3.1783435654718; Tue, 07 Jul 2026 07:47:34 -0700 (PDT) Received: from john-p8 ([98.97.43.67]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-387d100b5a1sm1253150a91.1.2026.07.07.07.47.33 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 07 Jul 2026 07:47:34 -0700 (PDT) Date: Tue, 7 Jul 2026 07:47:32 -0700 From: John Fastabend To: Vuln seeker Cyber Security Team Cc: bpf@vger.kernel.org Subject: Re: Responsible Disclosure: Heap Out-of-Bounds Write via Integer Underflow in libbpf parse_cpu_mask_str() (libbpf.c:14446) Message-ID: References: Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Disposition: inline In-Reply-To: On Fri, Jul 03, 2026 at 05:22:30PM +0500, Vuln seeker Cyber Security Team wrote: >Dear libbpf Security Team, [...] >libbpf's CPU mask parser. An integer underflow in parse_cpu_mask_str() >causes a memset to write far past a shrunk heap allocation, reachable >end-to-end through the public libbpf_num_possible_cpus() API. Send the fix seems worth checking to me if we are already checking start/end. If some app is exposing user input to this then I would push a report to them. [...] > - Any downstream consumer that feeds untrusted CPU-mask strings to > the >internal parse_cpu_mask_str helper directly Not sure why untrusted input is getting here but sure if someone is piping user input to libbpf let them know. I think if you have untrusted user input hitting libbpf you have bigger problems. [...] > > if (start < *mask_sz) > return -EINVAL; // "CPU range out of order or overlapping" > Send a fix. Thanks.