From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-ot0-f199.google.com (mail-ot0-f199.google.com [74.125.82.199]) by kanga.kvack.org (Postfix) with ESMTP id 6288B6B0007 for ; Tue, 1 May 2018 18:26:07 -0400 (EDT) Received: by mail-ot0-f199.google.com with SMTP id 106-v6so9879437otg.22 for ; Tue, 01 May 2018 15:26:07 -0700 (PDT) Received: from mail-sor-f65.google.com (mail-sor-f65.google.com. [209.85.220.65]) by mx.google.com with SMTPS id r96-v6sor4916415ota.33.2018.05.01.15.26.06 for (Google Transport Security); Tue, 01 May 2018 15:26:06 -0700 (PDT) Subject: Re: [PATCH] proc/kcore: Don't bounds check against address 0 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 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: owner-linux-mm@kvack.org List-ID: 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 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