Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760263Ab2EIQgk (ORCPT ); Wed, 9 May 2012 12:36:40 -0400 Received: from mail-yx0-f174.google.com ([209.85.213.174]:42235 "EHLO mail-yx0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1760230Ab2EIQgi convert rfc822-to-8bit (ORCPT ); Wed, 9 May 2012 12:36:38 -0400 MIME-Version: 1.0 In-Reply-To: <20120509162854.GM22082@ZenIV.linux.org.uk> References: <1336577114.3638.23.camel@lappy> <20120509161203.GK22082@ZenIV.linux.org.uk> <20120509162854.GM22082@ZenIV.linux.org.uk> From: Sasha Levin Date: Wed, 9 May 2012 18:36:17 +0200 Message-ID: Subject: Re: vfs: INFO: possible circular locking dependency detected To: Al Viro Cc: linux-fsdevel@vger.kernel.org, "linux-kernel@vger.kernel.org" Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1602 Lines: 34 On Wed, May 9, 2012 at 6:28 PM, Al Viro wrote: > On Wed, May 09, 2012 at 06:23:30PM +0200, Sasha Levin wrote: >> On Wed, May 9, 2012 at 6:12 PM, Al Viro wrote: >> > On Wed, May 09, 2012 at 05:25:14PM +0200, Sasha Levin wrote: >> >> Hi all, >> >> >> >> I've started seeing the following warning while fuzzing inside a KVM guest with the latest -next: >> > ? ? ? ?It's not a realistic attack, fortunately, since you need root >> > to get past open_exec() on any of those... ?Wait. ?How _did_ you get >> > past open_exec(), anyway? ?MAY_EXEC is not supposed to be granted on >> > anything that has no exec bits at all and AFAICS none of those files >> > have them. >> >> You could chmod +x and run them, no? > > Can't. ?proc_setattr() will give you -EPERM and refuse to do anything > if you call it with ATTR_MODE in ->ia_valid. If we look at /proc/irq/*/smp_affinity, which uses seq file ops, we can do this: sh-4.2# ls -al /proc/irq/5/smp_affinity -rw------- 1 root 0 0 May 9 16:35 /proc/irq/5/smp_affinity sh-4.2# chmod +x /proc/irq/5/smp_affinity sh-4.2# ls -al /proc/irq/5/smp_affinity -rwx--x--x 1 root 0 0 May 9 16:35 /proc/irq/5/smp_affinity sh-4.2# /proc/irq/5/smp_affinity /proc/irq/5/smp_affinity: line 1: 1f: command not found There are quite a lot of files under /proc that let me do that. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/