From patchwork Tue May 5 19:41:47 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Eric W. Biederman" X-Patchwork-Id: 11529805 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id DF5EF15E6 for ; Tue, 5 May 2020 19:45:17 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D0AD8206CC for ; Tue, 5 May 2020 19:45:17 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729054AbgEETpN (ORCPT ); Tue, 5 May 2020 15:45:13 -0400 Received: from out03.mta.xmission.com ([166.70.13.233]:55146 "EHLO out03.mta.xmission.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728076AbgEETpN (ORCPT ); Tue, 5 May 2020 15:45:13 -0400 Received: from in01.mta.xmission.com ([166.70.13.51]) by out03.mta.xmission.com with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.90_1) (envelope-from ) id 1jW3V9-00083B-LQ; Tue, 05 May 2020 13:45:12 -0600 Received: from ip68-227-160-95.om.om.cox.net ([68.227.160.95] helo=x220.xmission.com) by in01.mta.xmission.com with esmtpsa (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.87) (envelope-from ) id 1jW3V8-0003od-Jr; Tue, 05 May 2020 13:45:11 -0600 From: ebiederm@xmission.com (Eric W. Biederman) To: Cc: Linus Torvalds , Oleg Nesterov , Jann Horn , Kees Cook , Greg Ungerer , Rob Landley , Bernd Edlinger , , Al Viro , Alexey Dobriyan , Andrew Morton References: <87h7wujhmz.fsf@x220.int.ebiederm.org> Date: Tue, 05 May 2020 14:41:47 -0500 In-Reply-To: <87h7wujhmz.fsf@x220.int.ebiederm.org> (Eric W. Biederman's message of "Tue, 05 May 2020 14:39:32 -0500") Message-ID: <875zdajhj8.fsf@x220.int.ebiederm.org> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/26.1 (gnu/linux) MIME-Version: 1.0 X-XM-SPF: eid=1jW3V8-0003od-Jr;;;mid=<875zdajhj8.fsf@x220.int.ebiederm.org>;;;hst=in01.mta.xmission.com;;;ip=68.227.160.95;;;frm=ebiederm@xmission.com;;;spf=neutral X-XM-AID: U2FsdGVkX1/P9NxwY411o2elzyVOSNgU/+cN+kgzRws= X-SA-Exim-Connect-IP: 68.227.160.95 X-SA-Exim-Mail-From: ebiederm@xmission.com X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on sa02.xmission.com X-Spam-Level: * X-Spam-Status: No, score=1.3 required=8.0 tests=ALL_TRUSTED,BAYES_50, DCC_CHECK_NEGATIVE,T_TooManySym_01,XMNoVowels autolearn=disabled version=3.4.2 X-Spam-Virus: No X-Spam-Report: * -1.0 ALL_TRUSTED Passed through trusted hosts only via SMTP * 0.8 BAYES_50 BODY: Bayes spam probability is 40 to 60% * [score: 0.5000] * 1.5 XMNoVowels Alpha-numberic number with no vowels * -0.0 DCC_CHECK_NEGATIVE Not listed in DCC * [sa02 0; Body=1 Fuz1=1 Fuz2=1] * 0.0 T_TooManySym_01 4+ unique symbols in subject X-Spam-DCC: ; sa02 0; Body=1 Fuz1=1 Fuz2=1 X-Spam-Combo: *; X-Spam-Relay-Country: X-Spam-Timing: total 379 ms - load_scoreonly_sql: 0.03 (0.0%), signal_user_changed: 3.5 (0.9%), b_tie_ro: 2.4 (0.6%), parse: 0.67 (0.2%), extract_message_metadata: 9 (2.3%), get_uri_detail_list: 0.89 (0.2%), tests_pri_-1000: 11 (2.8%), tests_pri_-950: 1.01 (0.3%), tests_pri_-900: 0.81 (0.2%), tests_pri_-90: 68 (18.0%), check_bayes: 67 (17.7%), b_tokenize: 5 (1.4%), b_tok_get_all: 6 (1.5%), b_comp_prob: 1.36 (0.4%), b_tok_touch_all: 52 (13.6%), b_finish: 0.75 (0.2%), tests_pri_0: 276 (72.8%), check_dkim_signature: 0.45 (0.1%), check_dkim_adsp: 2.9 (0.8%), poll_dns_idle: 1.41 (0.4%), tests_pri_10: 1.80 (0.5%), tests_pri_500: 6 (1.5%), rewrite_mail: 0.00 (0.0%) Subject: [PATCH 2/7] exec: Make unlocking exec_update_mutex explict X-Spam-Flag: No X-SA-Exim-Version: 4.2.1 (built Thu, 05 May 2016 13:38:54 -0600) X-SA-Exim-Scanned: Yes (on in01.mta.xmission.com) Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org With install_exec_creds updated to follow immediately after setup_new_exec, the failure of unshare_sighand is the only code path where exec_update_mutex is held but not explicitly unlocked. Update that code path to explicitly unlock exec_update_mutex. Remove the unlocking of exec_update_mutex from free_bprm. Signed-off-by: "Eric W. Biederman" Reviewed-by: Kees Cook --- fs/exec.c | 6 +++--- include/linux/binfmts.h | 3 +-- 2 files changed, 4 insertions(+), 5 deletions(-) diff --git a/fs/exec.c b/fs/exec.c index 06b4c550af5d..6bd82a007bfc 100644 --- a/fs/exec.c +++ b/fs/exec.c @@ -1344,7 +1344,7 @@ int flush_old_exec(struct linux_binprm * bprm) */ retval = unshare_sighand(me); if (retval) - goto out; + goto out_unlock; set_fs(USER_DS); me->flags &= ~(PF_RANDOMIZE | PF_FORKNOEXEC | PF_KTHREAD | @@ -1361,6 +1361,8 @@ int flush_old_exec(struct linux_binprm * bprm) do_close_on_exec(me->files); return 0; +out_unlock: + mutex_unlock(&me->signal->exec_update_mutex); out: return retval; } @@ -1477,8 +1479,6 @@ static void free_bprm(struct linux_binprm *bprm) { free_arg_pages(bprm); if (bprm->cred) { - if (bprm->called_exec_mmap) - mutex_unlock(¤t->signal->exec_update_mutex); mutex_unlock(¤t->signal->cred_guard_mutex); abort_creds(bprm->cred); } diff --git a/include/linux/binfmts.h b/include/linux/binfmts.h index a345d9fed3d8..6f564b9ad882 100644 --- a/include/linux/binfmts.h +++ b/include/linux/binfmts.h @@ -47,8 +47,7 @@ struct linux_binprm { secureexec:1, /* * Set by flush_old_exec, when exec_mmap has been called. - * This is past the point of no return, when the - * exec_update_mutex has been taken. + * This is past the point of no return. */ called_exec_mmap:1; #ifdef __alpha__