From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759333AbZLJAzO (ORCPT ); Wed, 9 Dec 2009 19:55:14 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751330AbZLJAzK (ORCPT ); Wed, 9 Dec 2009 19:55:10 -0500 Received: from www.tglx.de ([62.245.132.106]:54092 "EHLO www.tglx.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1759097AbZLJAyX (ORCPT ); Wed, 9 Dec 2009 19:54:23 -0500 Message-Id: <20091210004703.187264393@linutronix.de> User-Agent: quilt/0.47-1 Date: Thu, 10 Dec 2009 00:53:12 -0000 From: Thomas Gleixner To: LKML Cc: "Paul E. McKenney" , Dipankar Sarma , Ingo Molnar , Peter Zijlstra , Oleg Nesterov , Al Viro , James Morris , David Howells , Andrew Morton , Linus Torvalds , linux-security-module@vger.kernel.org Subject: [patch 5/9] security: Use get_task_cred() in keyctl_session_to_parent() References: <20091210001308.247025548@linutronix.de> Content-Disposition: inline; filename=security-fix-missing-rcu-protection-of-__task_cred.patch Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Strictly this is not necessary today, but according to Paul McKenney it's not guaranteed that irq disabled regions will prevent RCU progress. That's a property of the current implementation. In preempt-rt this assumption is not true anymore. Use get_task_cred() to make this future proof. Signed-off-by: Thomas Gleixner Cc: James Morris Cc: linux-security-module@vger.kernel.org --- security/keys/keyctl.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) Index: linux-2.6-tip/security/keys/keyctl.c =================================================================== --- linux-2.6-tip.orig/security/keys/keyctl.c +++ linux-2.6-tip/security/keys/keyctl.c @@ -1237,7 +1237,7 @@ long keyctl_get_security(key_serial_t ke long keyctl_session_to_parent(void) { struct task_struct *me, *parent; - const struct cred *mycred, *pcred; + const struct cred *mycred, *pcred = NULL; struct cred *cred, *oldcred; key_ref_t keyring_r; int ret; @@ -1274,7 +1274,7 @@ long keyctl_session_to_parent(void) /* the parent and the child must have different session keyrings or * there's no point */ mycred = current_cred(); - pcred = __task_cred(parent); + pcred = get_task_cred(parent); if (mycred == pcred || mycred->tgcred->session_keyring == pcred->tgcred->session_keyring) goto already_same; @@ -1312,6 +1312,7 @@ long keyctl_session_to_parent(void) set_ti_thread_flag(task_thread_info(parent), TIF_NOTIFY_RESUME); write_unlock_irq(&tasklist_lock); + put_cred(pcred); if (oldcred) put_cred(oldcred); return 0; @@ -1321,6 +1322,8 @@ already_same: not_permitted: write_unlock_irq(&tasklist_lock); put_cred(cred); + if (pcred) + put_cred(pcred); return ret; error_keyring: