From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 4C31FC00140 for ; Mon, 15 Aug 2022 23:13:01 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1345958AbiHOXM7 (ORCPT ); Mon, 15 Aug 2022 19:12:59 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44046 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232933AbiHOXLg (ORCPT ); Mon, 15 Aug 2022 19:11:36 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8542238B3; Mon, 15 Aug 2022 13:00:17 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 99AEB612B8; Mon, 15 Aug 2022 20:00:16 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 8E38AC433C1; Mon, 15 Aug 2022 20:00:15 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1660593616; bh=HH4qPGidm0OUya6QXERfAKhEFrdc6+v3zuCV1SJ7ZWo=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=DvLgj34xtBjS79KJcY+X2oBoudgW4Gb+klj5T23u+xCtTyF0dAylqFXJbFO/9x9+g Wvwbbt5fDP5j4Gnw2FD6TNwygRfxb6JyalasyPYBMku91+ii0Kge/U8b257Rsac159 srLLmxvR8NtWNIVbvuLWl0R+jVzz9fgMC970ahpY= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Thadeu Lima de Souza Cascardo , Thomas Gleixner Subject: [PATCH 5.18 0976/1095] posix-cpu-timers: Cleanup CPU timers before freeing them during exec Date: Mon, 15 Aug 2022 20:06:15 +0200 Message-Id: <20220815180509.486593618@linuxfoundation.org> X-Mailer: git-send-email 2.37.2 In-Reply-To: <20220815180429.240518113@linuxfoundation.org> References: <20220815180429.240518113@linuxfoundation.org> User-Agent: quilt/0.67 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Thadeu Lima de Souza Cascardo commit e362359ace6f87c201531872486ff295df306d13 upstream. Commit 55e8c8eb2c7b ("posix-cpu-timers: Store a reference to a pid not a task") started looking up tasks by PID when deleting a CPU timer. When a non-leader thread calls execve, it will switch PIDs with the leader process. Then, as it calls exit_itimers, posix_cpu_timer_del cannot find the task because the timer still points out to the old PID. That means that armed timers won't be disarmed, that is, they won't be removed from the timerqueue_list. exit_itimers will still release their memory, and when that list is later processed, it leads to a use-after-free. Clean up the timers from the de-threaded task before freeing them. This prevents a reported use-after-free. Fixes: 55e8c8eb2c7b ("posix-cpu-timers: Store a reference to a pid not a task") Signed-off-by: Thadeu Lima de Souza Cascardo Signed-off-by: Thomas Gleixner Reviewed-by: Thomas Gleixner Cc: Link: https://lore.kernel.org/r/20220809170751.164716-1-cascardo@canonical.com Signed-off-by: Greg Kroah-Hartman --- fs/exec.c | 3 +++ 1 file changed, 3 insertions(+) --- a/fs/exec.c +++ b/fs/exec.c @@ -1297,6 +1297,9 @@ int begin_new_exec(struct linux_binprm * bprm->mm = NULL; #ifdef CONFIG_POSIX_TIMERS + spin_lock_irq(&me->sighand->siglock); + posix_cpu_timers_exit(me); + spin_unlock_irq(&me->sighand->siglock); exit_itimers(me); flush_itimer_signals(); #endif