From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-lj1-f177.google.com (mail-lj1-f177.google.com [209.85.208.177]) (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 1A38B4502B; Wed, 14 Aug 2024 17:10:14 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.208.177 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1723655416; cv=none; b=E/mfpC/YdKTqEjuv/mMSFVCpZc50HBGGlHEAnnDAE431MTNGkjPc6V1eYFhs8CsCyQky24oZu0/RcAskCwM1luAAeuiBMJSx6totqz9m0OKDXcYg3qFPhpL8bDWP7LPtCV906ee9lVZbApV08FUcObO/jVLVBfRCl2/ez94fCPE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1723655416; c=relaxed/simple; bh=F4XPMawEpVXT9q7pRj4NtWJkjyAA81vm0rr2VpJL9tI=; h=Date:From:To:Cc:Subject:Message-ID:MIME-Version:Content-Type: Content-Disposition; b=mTogRPGrgwhfOMQMXDYcSo4WrcQDQ4MM8GxE5rqdZSzkH2WfQaCleIgUB/xy8bUHAhPdyFwmS0ebggLUEf5ZWxgVHxnYkoKfROrjMMcjM2VoU7Um7bMvow5YMMH+dWngJZkMQnj8n+NssV0jiL8DIlzyI7Dh/m37YC3dzEeL68w= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=debian.org; spf=pass smtp.mailfrom=gmail.com; arc=none smtp.client-ip=209.85.208.177 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=debian.org Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Received: by mail-lj1-f177.google.com with SMTP id 38308e7fff4ca-2f032cb782dso1068431fa.3; Wed, 14 Aug 2024 10:10:14 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1723655413; x=1724260213; h=content-disposition:mime-version:message-id:subject:cc:to:from:date :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=7sP0prdJ764zDRhGrMOxeD1PYZLi3P8WVzp9dTBreHs=; b=JGhbgY8mtlubOMfvtFbBlXKCr3VDxVCUGuNctqVOLPLslG00L3L3FwcpVf+RQCu+mK X03J2fCIUGfd4hZUgI/vL+7rFz+2wkXj1RgqISQKWw8ykKYax8jWsGd9WU/seemDSdbN 2uwCJaxj2GJ0r2Xjr2/fDEM8RAwyK+CjC1CwYfU0dsqWNfeSoyvxWvzLyt/yAPYv6QzQ 5Xmha5DyuvTrTfYloVeIPYDBAsNmsuC2SfR8S8MSe9yxEASVfVfbMoRs1roNhXvJVhF2 V5VVxNQEYj4mQb7AX0VRWoxmvMP+2jTuJUml7z9W6137QooWidGcNc7rHmm13puML/XV +g3g== X-Forwarded-Encrypted: i=1; AJvYcCXi273ST6BSjrT914G6mloFY6MiI6iV0FbBiTrU9gk6vwj3y6sP4QDtEPED1Cv27VBtyRBwPUKflleyyy3IzlPBtL6JqNpiW6+s3rV/7W7BrE3J/ulNt+U9hM9xOCEaZ0ZfQb+L9+7c X-Gm-Message-State: AOJu0YxADe2Q+5EBti77PvUKzzotUD0KZ/+EuohlnUYIl+VSVe9rXAW4 zkCsaJHlgifyW7Tn+94DbULVO0Z598xFf+7/RD023uTlnHJeUfvn X-Google-Smtp-Source: AGHT+IH8Z01+eFXbFBwCYnLygKYJO8nh4RI5+IJx3TWPFQdiMFkE4hEKhkA7azYW55nofQIrBXQquw== X-Received: by 2002:a2e:a99f:0:b0:2ee:7dfe:d99c with SMTP id 38308e7fff4ca-2f3aa1f51a3mr23695561fa.31.1723655412783; Wed, 14 Aug 2024 10:10:12 -0700 (PDT) Received: from gmail.com (fwdproxy-lla-007.fbsv.net. [2a03:2880:30ff:7::face:b00c]) by smtp.gmail.com with ESMTPSA id 4fb4d7f45d1cf-5be9bb73800sm1569528a12.38.2024.08.14.10.10.11 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 14 Aug 2024 10:10:12 -0700 (PDT) Date: Wed, 14 Aug 2024 10:10:10 -0700 From: Breno Leitao To: kees@kernel.org, elver@google.com, andreyknvl@gmail.com, ryabinin.a.a@gmail.com Cc: kasan-dev@googlegroups.com, linux-hardening@vger.kernel.org, axboe@kernel.dk, asml.silence@gmail.com, netdev@vger.kernel.org Subject: UBSAN: annotation to skip sanitization in variable that will wrap Message-ID: Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Hello, I am seeing some signed-integer-overflow in percpu reference counters. UBSAN: signed-integer-overflow in ./arch/arm64/include/asm/atomic_lse.h:204:1 -9223372036854775808 - 1 cannot be represented in type 's64' (aka 'long long') Call trace: handle_overflow __ubsan_handle_sub_overflow percpu_ref_put_many css_put cgroup_sk_free __sk_destruct __sk_free sk_free unix_release_sock unix_release sock_close This overflow is probably happening in percpu_ref->percpu_ref_data->count. Looking at the code documentation, it seems that overflows are fine in per-cpu values. The lib/percpu-refcount.c code comment says: * Note that the counter on a particular cpu can (and will) wrap - this * is fine, when we go to shutdown the percpu counters will all sum to * the correct value Is there a way to annotate the code to tell UBSAN that this overflow is expected and it shouldn't be reported? Thanks --breno