From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pj1-f51.google.com (mail-pj1-f51.google.com [209.85.216.51]) (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 C7152173 for ; Wed, 18 Aug 2021 22:54:04 +0000 (UTC) Received: by mail-pj1-f51.google.com with SMTP id mq2-20020a17090b3802b0290178911d298bso3474385pjb.1 for ; Wed, 18 Aug 2021 15:54:04 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=Bdg/OtOV5wymBEUwuQlX5+GK5JjmwLGgSiZ+Tmmadzg=; b=bGU4j745GyvuoiOCvJ9XjMdyezUrxYO1pPcd3Nh9uTw2AHyNof0gLDjkyhM8xE1bpY ZhK4WiLLT0bHAnhPZz+LIR1+EgOwNsqitav2SEBVEKiVfgPXmLnjjumcy0TFltdAkpUp +Y/iv2y66lHJkcJw8yDjHLrdQLAKo5xhCntkA7/YsKW0wiAtv4Qvj7Ok2yu75nvP5VG/ kQ33sD5kcz6G3nunSMjMr3GEhOael40I5f0/SkDnOprQdLkOYlZpBPRnAiPwJ3is8bPU tVhgUeDxPTVKaaCpoehLowvGyCLbirnVXNHyIzEPJxHcN9722SczInchAhVN3qboCzK5 oo2w== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=Bdg/OtOV5wymBEUwuQlX5+GK5JjmwLGgSiZ+Tmmadzg=; b=dk7iBSMO+lEKO4qQt6XdBBP0MLbSqW9zKYKpyjaKkOHc3hdcsDdvpr8/+ThH7wQtWC 4aK2muF2Cm+1IME72M5NMKUnovxYMzDme/wc6kyuWqdffZGWgI5dlQq93W16OBRkkVU7 zb38TP2xqpkS+VjrgvQVuqE/bpQBIJvtT5KAJCy571QZe6M0HISNGvNhU6sF0BrtxlUk 1KUN0/SUigWV2ndF82DL0guKNXNSRl70qWJA6z0kBVwkbJZVTrgWErosfQTSKa5vqtvF tCGRLwLVgfKH+frU07jcHScxyjVkvF8WadocZMo1lvgAP5rnX7i/D61HEDXUDr7Naa2B sepA== X-Gm-Message-State: AOAM533/xHXKsplOPuPRv6GpU5+J9DMDxiUz0BYyGpe658ymfo5cHkxH 0IaKvxdDIDsd3LEsg20Pq/kJ5w== X-Google-Smtp-Source: ABdhPJzzXby04WbbyigGFBDREGEkGV8RqUxAeMQ0ojYzJgYocP/xgVxlZiD/Hh9heqjmIsz5yKhdZw== X-Received: by 2002:a17:90a:af88:: with SMTP id w8mr11746328pjq.104.1629327244194; Wed, 18 Aug 2021 15:54:04 -0700 (PDT) Received: from google.com (157.214.185.35.bc.googleusercontent.com. [35.185.214.157]) by smtp.gmail.com with ESMTPSA id s26sm894895pgv.46.2021.08.18.15.54.03 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 18 Aug 2021 15:54:03 -0700 (PDT) Date: Wed, 18 Aug 2021 22:53:58 +0000 From: Sean Christopherson To: Kees Cook Cc: linux-kernel@vger.kernel.org, Paolo Bonzini , Vitaly Kuznetsov , Wanpeng Li , Jim Mattson , Joerg Roedel , Thomas Gleixner , Ingo Molnar , Borislav Petkov , x86@kernel.org, "H. Peter Anvin" , kvm@vger.kernel.org, "Gustavo A. R. Silva" , Greg Kroah-Hartman , Andrew Morton , linux-wireless@vger.kernel.org, netdev@vger.kernel.org, dri-devel@lists.freedesktop.org, linux-staging@lists.linux.dev, linux-block@vger.kernel.org, linux-kbuild@vger.kernel.org, clang-built-linux@googlegroups.com, Rasmus Villemoes , linux-hardening@vger.kernel.org Subject: Re: [PATCH v2 53/63] KVM: x86: Use struct_group() to zero decode cache Message-ID: References: <20210818060533.3569517-1-keescook@chromium.org> <20210818060533.3569517-54-keescook@chromium.org> <202108180922.6C9E385A1@keescook> Precedence: bulk X-Mailing-List: linux-staging@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <202108180922.6C9E385A1@keescook> On Wed, Aug 18, 2021, Kees Cook wrote: > On Wed, Aug 18, 2021 at 03:11:28PM +0000, Sean Christopherson wrote: > > From dbdca1f4cd01fee418c252e54c360d518b2b1ad6 Mon Sep 17 00:00:00 2001 > > From: Sean Christopherson > > Date: Wed, 18 Aug 2021 08:03:08 -0700 > > Subject: [PATCH] KVM: x86: Replace memset() "optimization" with normal > > per-field writes > > > > Explicitly zero select fields in the emulator's decode cache instead of > > zeroing the fields via a gross memset() that spans six fields. gcc and > > clang are both clever enough to batch the first five fields into a single > > quadword MOV, i.e. memset() and individually zeroing generate identical > > code. > > > > Removing the wart also prepares KVM for FORTIFY_SOURCE performing > > compile-time and run-time field bounds checking for memset(). > > > > No functional change intended. > > > > Reported-by: Kees Cook > > Signed-off-by: Sean Christopherson > > Reviewed-by: Kees Cook > > Do you want me to take this patch into my tree, or do you want to carry > it for KVM directly? That's a Paolo question :-) What's the expected timeframe for landing stricter bounds checking? If it's 5.16 or later, the easiest thing would be to squeak this into 5.15.