Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753117AbbBSWLO (ORCPT ); Thu, 19 Feb 2015 17:11:14 -0500 Received: from www262.sakura.ne.jp ([202.181.97.72]:61234 "EHLO www262.sakura.ne.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752308AbbBSWLM (ORCPT ); Thu, 19 Feb 2015 17:11:12 -0500 To: dave@stgolabs.net Cc: akpm@linux-foundation.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, takedakn@nttdata.co.jp, linux-security-module@vger.kernel.org Subject: Re: [PATCH 3/3] tomoyo: robustify handling of mm->exe_file From: Tetsuo Handa References: <1424304641-28965-1-git-send-email-dbueso@suse.de> <1424304641-28965-4-git-send-email-dbueso@suse.de> <1424324307.18191.5.camel@stgolabs.net> <201502192007.AFI30725.tHFFOOMVFOQSLJ@I-love.SAKURA.ne.jp> <1424370153.18191.12.camel@stgolabs.net> In-Reply-To: <1424370153.18191.12.camel@stgolabs.net> Message-Id: <201502200711.EIH87066.HSOJLFFOtFVOQM@I-love.SAKURA.ne.jp> X-Mailer: Winbiff [Version 2.51 PL2] X-Accept-Language: ja,en,zh Date: Fri, 20 Feb 2015 07:11:02 +0900 Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1163 Lines: 22 Davidlohr Bueso wrote: > On Thu, 2015-02-19 at 20:07 +0900, Tetsuo Handa wrote: > > Why do we need to let the caller call path_put() ? > > There is no need to do like proc_exe_link() does, for > > tomoyo_get_exe() returns pathname as "char *". > > Having the pathname doesn't guarantee anything later, and thus doesn't > seem very robust in the manager call if it can be dropped during the > call... or can this never occur in this context? > tomoyo_get_exe() returns the pathname of executable of current thread. The executable of current thread cannot be changed while current thread is inside the manager call. Although the pathname of executable of current thread could be changed by other threads via namespace manipulation like pivot_root(), holding a reference guarantees nothing. Your patch helps for avoiding memory allocation with mmap_sem held, but does not robustify handling of mm->exe_file for tomoyo. -- 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/