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=-13.3 required=3.0 tests=BAYES_00,DKIMWL_WL_MED, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_IN_DEF_DKIM_WL 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 BDA91C43331 for ; Tue, 12 Jan 2021 00:33:45 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 97AB222D5B for ; Tue, 12 Jan 2021 00:33:45 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2404011AbhALAZl (ORCPT ); Mon, 11 Jan 2021 19:25:41 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59964 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2390737AbhAKWpn (ORCPT ); Mon, 11 Jan 2021 17:45:43 -0500 Received: from mail-oo1-xc35.google.com (mail-oo1-xc35.google.com [IPv6:2607:f8b0:4864:20::c35]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 0141EC061795 for ; Mon, 11 Jan 2021 14:45:03 -0800 (PST) Received: by mail-oo1-xc35.google.com with SMTP id i18so145669ooh.5 for ; Mon, 11 Jan 2021 14:45:02 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=O6kpvfJukcSfzCE8pUQQCjHIT6O76tXxg9rP/f6B+4o=; b=p1aPlWShuhKkImVn7MGucoVZAZix8VzDlfAzzEinRVGv+R4jXCLuH4buasWXMvHN8u p57itQKrg0IiSRt08vLyEpcZnCMOcYS2PfCM1cXymUb4rkiWMF3JIKt/NnIlBqMk/29k Guc04C9Q27972coInhcL2+HafSp/onmNdGzDPwIPeAay3qZtuU8vnznOoxDBbdvBIzfP sPafwQqEM5c9wi46verEsT5u7122qmDkjpnHjvlsgDWGYKXSfolsrAr8JCGbu3R+B36s 6MBakNPiacJm3HjXc5xHpHQ3K5vP0z9DzIE6GxH1U3ByJx1qSubOQpFngerO30sgjPyX g7TQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=O6kpvfJukcSfzCE8pUQQCjHIT6O76tXxg9rP/f6B+4o=; b=pYPdsr+cgTX9bLRCCskW4lReZtpgfPm71SAc1E+8K1yC4zNR0C2gXTQN02r36s+oG8 hYmrlB/DwFHuOLOmWdEnQBedfhQOPw03InvUvlIlgyHE+nKWVQ+tUoNFoyuJQqvM3cM+ ML8Cv4+A1yx8t6Cv8PWoBl/F2tQvp9A2RDpEFZZHC+6fOJYsVgo8LeWhQPN2+kkcgS+k T6m8v8aNyMDeOihq9IW0brZcaTdX+sAqi43fYNt5PcyPaoM/Gk9LeMEtFVzUW6Z1POft QiHzk4ia6/lDRQw/z4QOy/bxKeVnL1xXRm1eYG3mevIp6YqPXnrUmz8kl+TwZ2apApvp jg6g== X-Gm-Message-State: AOAM530xrD44bk5zqobWji+zHhDTTFNvlB95Hw/SV6HRwmKfybiTl1bw 9D0cALc30ftTnz02q9k9oNSjll4G/evbdWPFK1vKlQ== X-Google-Smtp-Source: ABdhPJzkhny7kvYdHxhBKmqcMFa1AfruRGU61uyaRwGVzukCfaf+okOYn9JpZnSnjjewZU6Ogd5CB9JmmBniRlmn8Wo= X-Received: by 2002:a4a:e294:: with SMTP id k20mr966042oot.82.1610405102002; Mon, 11 Jan 2021 14:45:02 -0800 (PST) MIME-Version: 1.0 References: <000000000000d5173d05b7097755@google.com> In-Reply-To: <000000000000d5173d05b7097755@google.com> From: Jim Mattson Date: Mon, 11 Jan 2021 14:44:50 -0800 Message-ID: Subject: Re: UBSAN: shift-out-of-bounds in kvm_vcpu_after_set_cpuid To: syzbot Cc: Borislav Petkov , "H . Peter Anvin" , Joerg Roedel , kvm list , LKML , Ingo Molnar , Paolo Bonzini , Sean Christopherson , syzkaller-bugs , Thomas Gleixner , Vitaly Kuznetsov , Wanpeng Li , "the arch/x86 maintainers" Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org It looks like userspace can possibly induce this by providing guest CPUID information with a "physical address width" of 64 in leaf 0x80000008. Perhaps cpuid_query_maxphyaddr() should just look at the low 5 bits of CPUID.80000008H:EAX? Better would be to return an error for out-of-range values, but I understand that the kvm community's stance is that, in general, guest CPUID information should not be validated by kvm. On Tue, Dec 22, 2020 at 12:36 AM syzbot wrote: > > Hello, > > syzbot found the following issue on: > > HEAD commit: 5e60366d Merge tag 'fallthrough-fixes-clang-5.11-rc1' of g.. > git tree: upstream > console output: https://syzkaller.appspot.com/x/log.txt?x=11c7046b500000 > kernel config: https://syzkaller.appspot.com/x/.config?x=db720fe37a6a41d8 > dashboard link: https://syzkaller.appspot.com/bug?extid=e87846c48bf72bc85311 > compiler: gcc (GCC) 10.1.0-syz 20200507 > userspace arch: i386 > > Unfortunately, I don't have any reproducer for this issue yet. > > IMPORTANT: if you fix the issue, please add the following tag to the commit: > Reported-by: syzbot+e87846c48bf72bc85311@syzkaller.appspotmail.com > > ================================================================================ > UBSAN: shift-out-of-bounds in arch/x86/kvm/mmu.h:52:16 > shift exponent 64 is too large for 64-bit type 'long long unsigned int' > CPU: 1 PID: 11156 Comm: syz-executor.1 Not tainted 5.10.0-syzkaller #0 > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 > Call Trace: > __dump_stack lib/dump_stack.c:79 [inline] > dump_stack+0x107/0x163 lib/dump_stack.c:120 > ubsan_epilogue+0xb/0x5a lib/ubsan.c:148 > __ubsan_handle_shift_out_of_bounds.cold+0xb1/0x181 lib/ubsan.c:395 > rsvd_bits arch/x86/kvm/mmu.h:52 [inline] > kvm_vcpu_after_set_cpuid.cold+0x35/0x3a arch/x86/kvm/cpuid.c:181 > kvm_vcpu_ioctl_set_cpuid+0x28e/0x970 arch/x86/kvm/cpuid.c:273 > kvm_arch_vcpu_ioctl+0x1091/0x2d70 arch/x86/kvm/x86.c:4699 > kvm_vcpu_ioctl+0x7b9/0xdb0 arch/x86/kvm/../../../virt/kvm/kvm_main.c:3386 > kvm_vcpu_compat_ioctl+0x1a2/0x340 arch/x86/kvm/../../../virt/kvm/kvm_main.c:3430 > __do_compat_sys_ioctl+0x1d3/0x230 fs/ioctl.c:842 > do_syscall_32_irqs_on arch/x86/entry/common.c:78 [inline] > __do_fast_syscall_32+0x56/0x80 arch/x86/entry/common.c:137 > do_fast_syscall_32+0x2f/0x70 arch/x86/entry/common.c:160 > entry_SYSENTER_compat_after_hwframe+0x4d/0x5c > RIP: 0023:0xf7fe8549 > Code: b8 01 10 06 03 74 b4 01 10 07 03 74 b0 01 10 08 03 74 d8 01 00 00 00 00 00 00 00 00 00 00 00 00 00 51 52 55 89 e5 0f 34 cd 80 <5d> 5a 59 c3 90 90 90 90 eb 0d 90 90 90 90 90 90 90 90 90 90 90 90 > RSP: 002b:00000000f55e20cc EFLAGS: 00000296 ORIG_RAX: 0000000000000036 > RAX: ffffffffffffffda RBX: 0000000000000005 RCX: 000000004008ae8a > RDX: 00000000200000c0 RSI: 0000000000000000 RDI: 0000000000000000 > RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000 > R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000 > R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000 > ================================================================================ > > > --- > This report is generated by a bot. It may contain errors. > See https://goo.gl/tpsmEJ for more information about syzbot. > syzbot engineers can be reached at syzkaller@googlegroups.com. > > syzbot will keep track of this issue. See: > https://goo.gl/tpsmEJ#status for how to communicate with syzbot.