From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751537AbdKTWQS (ORCPT ); Mon, 20 Nov 2017 17:16:18 -0500 Received: from mail.linuxfoundation.org ([140.211.169.12]:43512 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751154AbdKTWQQ (ORCPT ); Mon, 20 Nov 2017 17:16:16 -0500 Date: Mon, 20 Nov 2017 14:16:14 -0800 From: Andrew Morton To: Alexey Dobriyan Cc: linux-kernel@vger.kernel.org, xemul@virtuozzo.com Subject: Re: [PATCH] proc: fix /proc/*/map_files lookup Message-Id: <20171120141614.b1c4d42da8503963d887917b@linux-foundation.org> In-Reply-To: <20171120212706.GA14325@avx2> References: <20171120212706.GA14325@avx2> X-Mailer: Sylpheed 3.4.1 (GTK+ 2.24.23; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 21 Nov 2017 00:27:06 +0300 Alexey Dobriyan wrote: > Current code does: > > if (sscanf(dentry->d_name.name, "%lx-%lx", start, end) != 2) > > However sscanf() is broken garbage. > > It silently accepts whitespace between format specifiers > (did you know that?). > > It silently accepts valid strings which result in integer overflow. > > Do not use sscanf() for any even remotely reliable parsing code. > > OK > # readlink '/proc/1/map_files/55a23af39000-55a23b05b000' > /lib/systemd/systemd > > broken > # readlink '/proc/1/map_files/ 55a23af39000-55a23b05b000' > /lib/systemd/systemd > > broken > # readlink '/proc/1/map_files/55a23af39000-55a23b05b000 ' > /lib/systemd/systemd > > very broken > # readlink '/proc/1/map_files/1000000000000000055a23af39000-55a23b05b000' > /lib/systemd/systemd > > Signed-off-by: Alexey Dobriyan > Cc: stable@kernel.org OK, but why is this a problem worthy of backporting into -stable kernels?