From patchwork Wed Sep 5 19:35:21 2012 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Tim Gardner X-Patchwork-Id: 181928 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from chlorine.canonical.com (chlorine.canonical.com [91.189.94.204]) by ozlabs.org (Postfix) with ESMTP id 761552C0094 for ; Thu, 6 Sep 2012 05:35:35 +1000 (EST) Received: from localhost ([127.0.0.1] helo=chlorine.canonical.com) by chlorine.canonical.com with esmtp (Exim 4.71) (envelope-from ) id 1T9LMb-0006mj-2g; Wed, 05 Sep 2012 19:34:13 +0000 Received: from mail.tpi.com ([70.99.223.143]) by chlorine.canonical.com with esmtp (Exim 4.71) (envelope-from ) id 1T9LMY-0006mV-IN for kernel-team@lists.ubuntu.com; Wed, 05 Sep 2012 19:34:10 +0000 Received: from salmon.rtg.net (mail.tpi.com [70.99.223.143]) by mail.tpi.com (Postfix) with ESMTP id EB3F1320AE3 for ; Wed, 5 Sep 2012 12:34:00 -0700 (PDT) Received: by salmon.rtg.net (Postfix, from userid 1000) id 8EE2C20BE8; Wed, 5 Sep 2012 13:35:21 -0600 (MDT) From: Tim Gardner To: kernel-team@lists.ubuntu.com Subject: [PATCH Lucid CVE-2012-2745] cred: copy_process() should clear child->replacement_session_keyring Date: Wed, 5 Sep 2012 13:35:21 -0600 Message-Id: <1346873721-21543-1-git-send-email-tim.gardner@canonical.com> X-Mailer: git-send-email 1.7.9.5 X-BeenThere: kernel-team@lists.ubuntu.com X-Mailman-Version: 2.1.13 Precedence: list List-Id: Kernel team discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Sender: kernel-team-bounces@lists.ubuntu.com Errors-To: kernel-team-bounces@lists.ubuntu.com From: Oleg Nesterov CVE-2012-2745 BugLink: http://bugs.launchpad.net/bugs/1023535 keyctl_session_to_parent(task) sets ->replacement_session_keyring, it should be processed and cleared by key_replace_session_keyring(). However, this task can fork before it notices TIF_NOTIFY_RESUME and the new child gets the bogus ->replacement_session_keyring copied by dup_task_struct(). This is obviously wrong and, if nothing else, this leads to put_cred(already_freed_cred). change copy_creds() to clear this member. If copy_process() fails before this point the wrong ->replacement_session_keyring doesn't matter, exit_creds() won't be called. Cc: Signed-off-by: Oleg Nesterov Acked-by: David Howells Signed-off-by: Linus Torvalds (back ported from commit 79549c6dfda0603dba9a70a53467ce62d9335c33) Signed-off-by: Tim Gardner --- kernel/cred.c | 1 + 1 file changed, 1 insertion(+) diff --git a/kernel/cred.c b/kernel/cred.c index 0b5b5fc..6ffd433 100644 --- a/kernel/cred.c +++ b/kernel/cred.c @@ -442,6 +442,7 @@ int copy_creds(struct task_struct *p, unsigned long clone_flags) int ret; mutex_init(&p->cred_guard_mutex); + p->replacement_session_keyring = NULL; if ( #ifdef CONFIG_KEYS