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=-5.6 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 0DEE5C433E2 for ; Mon, 14 Sep 2020 16:55:21 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A32BC217BA for ; Mon, 14 Sep 2020 16:55:20 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="dndrQIoM" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726360AbgINQzS (ORCPT ); Mon, 14 Sep 2020 12:55:18 -0400 Received: from us-smtp-delivery-1.mimecast.com ([205.139.110.120]:47384 "EHLO us-smtp-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726172AbgINQtr (ORCPT ); Mon, 14 Sep 2020 12:49:47 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1600102176; 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=0mbvYuND3lRjyeQVUwoOKkvygq3qV13+cH0GnP7z9uA=; b=dndrQIoMPV5FZKBkE7c1JYpSC8VYIWTu9kM3apPuIgWQQghsj993bgP1Dyn7xHCJWDAWyz USVN5xET7Sv0EIG7bpuvBW9l4QfSC87EAlph2RrlejBgVyrntum4dY3udBPJNUUYMI3ARS JOdPQo/+1tuFz32GYznMbVS5K5/6vO4= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-584-hsI6WwqjPLqpr6ELOWLFww-1; Mon, 14 Sep 2020 12:49:32 -0400 X-MC-Unique: hsI6WwqjPLqpr6ELOWLFww-1 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id C72D018B9F01; Mon, 14 Sep 2020 16:49:30 +0000 (UTC) Received: from treble (ovpn-115-26.rdu2.redhat.com [10.10.115.26]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 425267512A; Mon, 14 Sep 2020 16:49:29 +0000 (UTC) Date: Mon, 14 Sep 2020 11:49:27 -0500 From: Josh Poimboeuf To: Thomas Gleixner Cc: syzbot , alexandre.chartre@oracle.com, bp@alien8.de, hpa@zytor.com, linux-kernel@vger.kernel.org, luto@kernel.org, mingo@redhat.com, peterz@infradead.org, syzkaller-bugs@googlegroups.com, x86@kernel.org Subject: Re: WARNING: can't access registers at asm_sysvec_call_function_single Message-ID: <20200914164927.t476jnlkmdibgqvn@treble> References: <0000000000002b02cf05aed302f3@google.com> <87lfhdpeum.fsf@nanos.tec.linutronix.de> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <87lfhdpeum.fsf@nanos.tec.linutronix.de> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sun, Sep 13, 2020 at 11:05:21PM +0200, Thomas Gleixner wrote: > On Tue, Sep 08 2020 at 13:16, syzbot wrote: > > > Hello, > > > > syzbot found the following issue on: > > > > HEAD commit: f4d51dff Linux 5.9-rc4 > > git tree: upstream > > console output: https://syzkaller.appspot.com/x/log.txt?x=1455d4f9900000 > > kernel config: https://syzkaller.appspot.com/x/.config?x=a9075b36a6ae26c9 > > dashboard link: https://syzkaller.appspot.com/bug?extid=bc9dbf05dcc151e9b972 > > compiler: gcc (GCC) 10.1.0-syz 20200507 > > > > 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+bc9dbf05dcc151e9b972@syzkaller.appspotmail.com > > > > WARNING: can't access registers at asm_sysvec_call_function_single+0x12/0x20 arch/x86/include/asm/idtentry.h:589 > > That's the ORC unwinder complaining, but I have no idea why... 0000000000000cd0 : cd0: 90 nop cd1: 90 nop cd2: 90 nop cd3: 6a ff pushq $0xffffffffffffffff cd5: e8 b6 03 00 00 callq 1090 cda: 48 89 e7 mov %rsp,%rdi cdd: e8 00 00 00 00 callq ce2 cde: R_X86_64_PLT32 sysvec_call_function_single-0x4 ce2: e9 69 04 00 00 jmpq 1150 ce7: 66 0f 1f 84 00 00 00 nopw 0x0(%rax,%rax,1) cee: 00 00 This is a head scratcher. The ORC data looks ok, at least when I build it on my system. It's expecting to find pt_regs at the top of the stack after returning from sysvec_call_function_single(). But it can't dereference the regs for some reason. So either it's a bug in ORC data or unwinder (not likely) or the stack pointer got corrupted somehow (also seems unlikely)... -- Josh