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=-0.8 required=3.0 tests=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 ECB4AC4332B for ; Fri, 20 Mar 2020 15:23:01 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id CDAC92072D for ; Fri, 20 Mar 2020 15:23:01 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727422AbgCTPXA (ORCPT ); Fri, 20 Mar 2020 11:23:00 -0400 Received: from Galois.linutronix.de ([193.142.43.55]:36246 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726843AbgCTPXA (ORCPT ); Fri, 20 Mar 2020 11:23:00 -0400 Received: from p5de0bf0b.dip0.t-ipconnect.de ([93.224.191.11] helo=nanos.tec.linutronix.de) by Galois.linutronix.de with esmtpsa (TLS1.2:DHE_RSA_AES_256_CBC_SHA256:256) (Exim 4.80) (envelope-from ) id 1jFJU3-0006eY-EQ; Fri, 20 Mar 2020 16:22:51 +0100 Received: by nanos.tec.linutronix.de (Postfix, from userid 1000) id C62A5100375; Fri, 20 Mar 2020 16:22:50 +0100 (CET) From: Thomas Gleixner To: Paolo Bonzini , linux-kernel@vger.kernel.org, kvm@vger.kernel.org Cc: syzbot+00be5da1d75f1cc95f6b@syzkaller.appspotmail.com, Sean Christopherson Subject: Re: [PATCH] KVM: x86: remove bogus user-triggerable WARN_ON In-Reply-To: <20200319174318.20752-1-pbonzini@redhat.com> References: <20200319174318.20752-1-pbonzini@redhat.com> Date: Fri, 20 Mar 2020 16:22:50 +0100 Message-ID: <87o8sr59v9.fsf@nanos.tec.linutronix.de> MIME-Version: 1.0 Content-Type: text/plain X-Linutronix-Spam-Score: -1.0 X-Linutronix-Spam-Level: - X-Linutronix-Spam-Status: No , -1.0 points, 5.0 required, ALL_TRUSTED=-1,SHORTCIRCUIT=-0.0001 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Paolo Bonzini writes: > The WARN_ON is essentially comparing a user-provided value with 0. It is > trivial to trigger it just by passing garbage to KVM_SET_CLOCK. Guests > can break if you do so, but if it hurts when you do like this just do not > do it. Yes, it's a user provided value and it's completely unchecked. If that value is bogus then the guest will go sideways because timekeeping is completely busted. At least you should explain WHY you don't care. Thanks, tglx