From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 062EFC43460 for ; Thu, 1 Apr 2021 09:08:52 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A4B8F610CE for ; Thu, 1 Apr 2021 09:08:51 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233670AbhDAJIU (ORCPT ); Thu, 1 Apr 2021 05:08:20 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]:32933 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229612AbhDAJIR (ORCPT ); Thu, 1 Apr 2021 05:08:17 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1617268097; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=SH8q6v7mosb9ZWkhGf8eANcJIvuHX/dVnNgdkFE16jE=; b=JyuCQVPFwIp/3uxqt6W7vC6AlxMS+8uw2UNA7rWHqxguau+l+0eazFFlNzbYH4llmylV4k px3LV4973LiLlktBRLaZmI4uSansLUVeRB6Zt1DH2lxIVDRchJIqMpqjNk+pkoMd+fny94 cKGqt2iTSR/KCXwKZVIyxv3+JwWPeTE= Received: from mail-ej1-f72.google.com (mail-ej1-f72.google.com [209.85.218.72]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-322-YjwvknXoOcWuym9LEcrhtQ-1; Thu, 01 Apr 2021 05:08:16 -0400 X-MC-Unique: YjwvknXoOcWuym9LEcrhtQ-1 Received: by mail-ej1-f72.google.com with SMTP id e13so1934433ejd.21 for ; Thu, 01 Apr 2021 02:08:15 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:in-reply-to:references:date :message-id:mime-version; bh=SH8q6v7mosb9ZWkhGf8eANcJIvuHX/dVnNgdkFE16jE=; b=YCMrmmO8u8tGP6Ll6wCyykHB5y7qnkqc/J77z+PEC2ywQE7jYpRVCKRQvBRKIBp34S 0bgAHrEUJ5Pj9oYOaH1X193LaSGlKeXaDJXp519HqTfYjGzUZGA190sMCQjPWaw/4LTK Ly5ULhweWj28XFmW4NAWkT2TvQDKsWNY+WBvQR1SBfDY1x0qWNg8Op6tRaVYZb/MlJEf 4/xTJLf69rbVjIWEEcHtv8SVG6R+OpWdaAbLUhaBFOIWgMJZo0ZS/G56oaV4NMlwyJ/I b1m7Maaz7nJgRw3r6ZAMK2CYeNdk1Diiy5+6V5OZzskNcAAIOBTP8wZ4UjsOuJUwJg0I MzQA== X-Gm-Message-State: AOAM531stjjl9iAfsGC9GjCKOgldRYw5ZXryqGmdKiCzNMgE6ZnzVzVS XymKij2XVNYpUBnXtKgFD9cND7vpmOL8JC2lrn6G1ei/mz4i1v1q0uxiCUxqsSBerHhGzDnMO2f rYdK2zDvFciX/ X-Received: by 2002:aa7:d296:: with SMTP id w22mr9132646edq.150.1617268094915; Thu, 01 Apr 2021 02:08:14 -0700 (PDT) X-Google-Smtp-Source: ABdhPJxkaDtD/zV8/+g4vA8exSjAqnDTdsDQz0T3HuSz8w49b9Wf/JUk9n3MB5ubq9QTsnrpDORKRg== X-Received: by 2002:aa7:d296:: with SMTP id w22mr9132630edq.150.1617268094789; Thu, 01 Apr 2021 02:08:14 -0700 (PDT) Received: from vitty.brq.redhat.com (g-server-2.ign.cz. [91.219.240.2]) by smtp.gmail.com with ESMTPSA id x4sm2967618edd.58.2021.04.01.02.08.13 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 01 Apr 2021 02:08:14 -0700 (PDT) From: Vitaly Kuznetsov To: Sean Christopherson , Yang Li Cc: pbonzini@redhat.com, wanpengli@tencent.com, jmattson@google.com, joro@8bytes.org, tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, x86@kernel.org, hpa@zytor.com, kvm@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] KVM: x86: Fix potential memory access error In-Reply-To: References: <1617182122-112315-1-git-send-email-yang.lee@linux.alibaba.com> Date: Thu, 01 Apr 2021 11:08:13 +0200 Message-ID: <87mtuis77m.fsf@vitty.brq.redhat.com> MIME-Version: 1.0 Content-Type: text/plain Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org Sean Christopherson writes: > On Wed, Mar 31, 2021, Yang Li wrote: >> Using __set_bit() to set a bit in an integer is not a good idea, since >> the function expects an unsigned long as argument, which can be 64bit wide. >> Coverity reports this problem as >> >> High:Out-of-bounds access(INCOMPATIBLE_CAST) >> CWE119: Out-of-bounds access to a scalar >> Pointer "&vcpu->arch.regs_avail" points to an object whose effective >> type is "unsigned int" (32 bits, unsigned) but is dereferenced as a >> wider "unsigned long" (64 bits, unsigned). This may lead to memory >> corruption. >> >> /home/heyuan.shy/git-repo/linux/arch/x86/kvm/kvm_cache_regs.h: >> kvm_register_is_available >> >> Just use BIT instead. > > Meh, we're hosed either way. Using BIT() will either result in undefined > behavior due to SHL shifting beyond the size of a u64, or setting random bits > if the truncated shift ends up being less than 63. > A stupid question: why can't we just make 'regs_avail'/'regs_dirty' 'unsigned long' and drop a bunch of '(unsigned long *)' casts? -- Vitaly