From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <linux-kernel-owner@vger.kernel.org>
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
        id S1751844AbdK3ThS (ORCPT <rfc822;w@1wt.eu>);
        Thu, 30 Nov 2017 14:37:18 -0500
Received: from mail.kernel.org ([198.145.29.99]:34030 "EHLO mail.kernel.org"
        rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP
        id S1751591AbdK3ThR (ORCPT <rfc822;linux-kernel@vger.kernel.org>);
        Thu, 30 Nov 2017 14:37:17 -0500
DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org DFD412170E
Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=kernel.org
Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=acme@kernel.org
Date: Thu, 30 Nov 2017 16:37:12 -0300
From: Arnaldo Carvalho de Melo <acme@kernel.org>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Fengguang Wu <fengguang.wu@intel.com>, linux-kernel@vger.kernel.org,
        Wang Nan <wangnan0@huawei.com>, Ingo Molnar <mingo@redhat.com>,
        Alexander Shishkin <alexander.shishkin@linux.intel.com>,
        Jiri Olsa <jolsa@redhat.com>, Namhyung Kim <namhyung@kernel.org>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Will Deacon <will.deacon@arm.com>, lkp@01.org,
        Dmitry Vyukov <dvyukov@google.com>, kasan-dev@googlegroups.com
Subject: Re: BUG: KASAN: slab-out-of-bounds in perf_callchain_user+0x494/0x530
Message-ID: <20171130193712.GU3298@kernel.org>
References: <20171130023218.g2y35nn4zyufqk6t@wfg-t540p.sh.intel.com>
 <20171130082026.ih7esfpn4wfsfoge@hirez.programming.kicks-ass.net>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <20171130082026.ih7esfpn4wfsfoge@hirez.programming.kicks-ass.net>
X-Url: http://acmel.wordpress.com
User-Agent: Mutt/1.9.1 (2017-09-22)
Sender: linux-kernel-owner@vger.kernel.org
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

Em Thu, Nov 30, 2017 at 09:20:26AM +0100, Peter Zijlstra escreveu:
> On Thu, Nov 30, 2017 at 10:32:19AM +0800, Fengguang Wu wrote:
> > Hello,
> > 
> > FYI this happens in mainline kernel 4.15.0-rc1.
> > It looks like a new regression and hard to bisect.
> > 
> > It occurs in 1 out of 57 boots.
> > 
> > [   10.009610] chown (367) used greatest stack depth: 26944 bytes left
> > Kernel tests: Boot OK!
> > [   30.357729] trinity-main uses obsolete (PF_INET,SOCK_PACKET)
> > [   31.301433] sock: process `trinity-main' is using obsolete setsockopt SO_BSDCOMPAT
> > [   31.310289] ==================================================================
> > [   31.311490] BUG: KASAN: slab-out-of-bounds in perf_callchain_user+0x494/0x530:
> > 						perf_callchain_store at include/linux/perf_event.h:1128
> > 						 (inlined by) perf_callchain_user at arch/x86/events/core.c:2485
> 
> I don't think we recently changed anything here...
> 
> But I do have vague memories of something being off here; I never quite
> could penetrate the max_stack / contexts_maxed stuff, and istr acme was
> going to have a peek.
 
Sure, but I saw some backward ring buffer stuff in there as well, no?
IIRC that came after the max-stack code, Adding Wang to the CC list.

- Arnaldo