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 S1751958AbdK3IUg (ORCPT <rfc822;w@1wt.eu>);
        Thu, 30 Nov 2017 03:20:36 -0500
Received: from bombadil.infradead.org ([65.50.211.133]:38651 "EHLO
        bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org
        with ESMTP id S1751178AbdK3IUe (ORCPT
        <rfc822;linux-kernel@vger.kernel.org>);
        Thu, 30 Nov 2017 03:20:34 -0500
Date: Thu, 30 Nov 2017 09:20:26 +0100
From: Peter Zijlstra <peterz@infradead.org>
To: Fengguang Wu <fengguang.wu@intel.com>
Cc: linux-kernel@vger.kernel.org, Ingo Molnar <mingo@redhat.com>,
        Arnaldo Carvalho de Melo <acme@kernel.org>,
        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: <20171130082026.ih7esfpn4wfsfoge@hirez.programming.kicks-ass.net>
References: <20171130023218.g2y35nn4zyufqk6t@wfg-t540p.sh.intel.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <20171130023218.g2y35nn4zyufqk6t@wfg-t540p.sh.intel.com>
User-Agent: NeoMutt/20170609 (1.8.3)
Sender: linux-kernel-owner@vger.kernel.org
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

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.