From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932102AbaISPmS (ORCPT ); Fri, 19 Sep 2014 11:42:18 -0400 Received: from mx1.redhat.com ([209.132.183.28]:4273 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753398AbaISPmR (ORCPT ); Fri, 19 Sep 2014 11:42:17 -0400 From: Richard Guy Briggs To: linux-security-module@vger.kernel.org, linux-audit@redhat.com, linux-kernel@vger.kernel.org Cc: Richard Guy Briggs , pmoore@redhat.com, eparis@redhat.com, sgrubb@redhat.com, Tetsuo Handa Subject: [PATCH] lsm: get comm using lock to avoid race in string printing Date: Fri, 19 Sep 2014 11:41:15 -0400 Message-Id: <735f28048636878e638add7d6129a8c2fd79a09e.1411141022.git.rgb@redhat.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org When task->comm is passed directly to audit_log_untrustedstring() without getting a copy or using the task_lock, there is a race that could happen that would output a NULL (\0) in the output string that would effectively truncate the rest of the report text after the comm= field in the audit, losing fields. Use get_task_comm() to get a copy while acquiring the task_lock to prevent this and to prevent the result from being a mixture of old and new values of comm. Tetsuo Handa Signed-off-by: Richard Guy Briggs --- I've manually checked for locking issues and found none. I've also enabled all the kernel lock debugging options and it came up clean. security/lsm_audit.c | 5 +++-- 1 files changed, 3 insertions(+), 2 deletions(-) diff --git a/security/lsm_audit.c b/security/lsm_audit.c index 69fdf3b..4773b91 100644 --- a/security/lsm_audit.c +++ b/security/lsm_audit.c @@ -212,6 +212,7 @@ static void dump_common_audit_data(struct audit_buffer *ab, struct common_audit_data *a) { struct task_struct *tsk = current; + char comm[sizeof(tsk->comm)]; /* * To keep stack sizes in check force programers to notice if they @@ -221,7 +222,7 @@ static void dump_common_audit_data(struct audit_buffer *ab, BUILD_BUG_ON(sizeof(a->u) > sizeof(void *)*2); audit_log_format(ab, " pid=%d comm=", task_pid_nr(tsk)); - audit_log_untrustedstring(ab, tsk->comm); + audit_log_untrustedstring(ab, get_task_comm(comm, tsk)); switch (a->type) { case LSM_AUDIT_DATA_NONE: @@ -282,7 +283,7 @@ static void dump_common_audit_data(struct audit_buffer *ab, pid_t pid = task_pid_nr(tsk); if (pid) { audit_log_format(ab, " pid=%d comm=", pid); - audit_log_untrustedstring(ab, tsk->comm); + audit_log_untrustedstring(ab, get_task_comm(comm, tsk)); } } break; -- 1.7.1