From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751302AbeEAW0H (ORCPT ); Tue, 1 May 2018 18:26:07 -0400 Received: from mail-ot0-f193.google.com ([74.125.82.193]:42353 "EHLO mail-ot0-f193.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751069AbeEAW0G (ORCPT ); Tue, 1 May 2018 18:26:06 -0400 X-Google-Smtp-Source: AB8JxZqigOX3a9p9j+pUfqj9ooEL2gK8l2Ib655BaK2/9joUHk+rReCfmbYZV/ZZaFqmqgHp38CBWA== Subject: Re: [PATCH] proc/kcore: Don't bounds check against address 0 To: Andrew Morton Cc: Dave Anderson , Kees Cook , linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-arm-kernel@lists.infradead.org, Ard Biesheuvel , Ingo Molnar , Andi Kleen References: <1039518799.26129578.1525185916272.JavaMail.zimbra@redhat.com> <20180501201143.15121-1-labbott@redhat.com> <20180501144604.1cf872e7938bffc01a26349f@linux-foundation.org> From: Laura Abbott Message-ID: <4db64722-47b5-767c-4090-bdd9c1522e96@redhat.com> Date: Tue, 1 May 2018 15:26:00 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.7.0 MIME-Version: 1.0 In-Reply-To: <20180501144604.1cf872e7938bffc01a26349f@linux-foundation.org> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 05/01/2018 02:46 PM, Andrew Morton wrote: > On Tue, 1 May 2018 13:11:43 -0700 Laura Abbott wrote: > >> The existing kcore code checks for bad addresses against >> __va(0) with the assumption that this is the lowest address >> on the system. This may not hold true on some systems (e.g. >> arm64) and produce overflows and crashes. Switch to using >> other functions to validate the address range. >> >> Tested-by: Dave Anderson >> Signed-off-by: Laura Abbott >> --- >> I took your previous comments as a tested by, please let me know if that >> was wrong. This should probably just go through -mm. I don't think this >> is necessary for stable but I can request it later if necessary. > > I'm surprised. "overflows and crashes" sounds rather serious?? > It's currently only seen on arm64 and it's not clear if anyone wants to use that particular combination on a stable release. I think a better phrase is "this is not urgent for stable". Thanks, Laura