From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Cyrus-Session-Id: sloti22d1t05-1841884-1518709686-2-5386180227891748845 X-Sieve: CMU Sieve 3.0 X-Spam-known-sender: no X-Spam-score: 0.0 X-Spam-hits: BAYES_00 -1.9, HEADER_FROM_DIFFERENT_DOMAINS 0.001, ME_NOAUTH 0.01, RCVD_IN_DNSWL_HI -5, T_RP_MATCHES_RCVD -0.01, LANGUAGES en, BAYES_USED global, SA_VERSION 3.4.0 X-Spam-source: IP='209.132.180.67', Host='vger.kernel.org', Country='US', FromHeader='org', MailFrom='org' X-Spam-charsets: plain='UTF-8' X-Resolved-to: greg@kroah.com X-Delivered-to: greg@kroah.com X-Mail-from: stable-owner@vger.kernel.org ARC-Seal: i=1; a=rsa-sha256; cv=none; d=messagingengine.com; s=arctest; t=1518709685; b=VYDc6EfS9dZ0PfSkvvO6ikeWH7GlWDSDL2KqxzSqgOdPZN9 w+DaMBtmcRxQ4mpgquRZdzSVzW9dEm9WEWkDplcrtXhOiZLvjsAlZLF11lUqKnNq Ae2qF15BqTyAF21Hg7FYQTRJEQPIhY3duh6y+ba7Z5K8Ey9bCp5NbVfwMSY2URlx 41H6t5urN8wNXpvq4Xqfdvo76/81rm1BY7B1JQckr8VCFYwWPLsYN0I5qPajd3iG BTNzJ1WfQ2N6eE8EF+vTTUyGtxl1BQpz30ky1YUUwvitNpJTjtA4OGIDyfnJ18OS G6VvGrN7g02e0TE4Y9HW0IrESPXdbKYuEZPDbLA== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d= messagingengine.com; h=from:to:cc:subject:date:message-id :in-reply-to:references:mime-version:content-type:sender :list-id; s=arctest; t=1518709685; bh=7MjV7CmF9j/weCNRcn0fI4D9fB fUusRbERoubk/z9ro=; b=q9JypGYdvOKXG3KrJSSwDbfZ5smx2KTxd1+xV3oree qCUC7ZAv7dPhOLoLvl22vFdt4KNixlwizBE7zZtYDgrixpAUQ0oBOblVZls3Ppaw emI6ENaDf8hRArfgrJTPcVUgIoXGgZOv9mY00KXrzDHJjQLfJIO3MJc7Gw+PgEY4 Vm+AktW/Rb13GhaabKgqc+WJrrsK370u5xUE+wpk6dNFAf+DqLIYWIgBQZL/zVBx Pys8ij0vQs78CDGd+EI5+n3jGs1nraexZxI0XsZZzdw0aX3ZZJ+a716oQ9CAlvKb nCgJDtkwdsBMP3fIaV6wpRlHnSiY2VY2GnfTPGzatnrQ== ARC-Authentication-Results: i=1; mx1.messagingengine.com; arc=none (no signatures found); dkim=none (no signatures found); dmarc=none (p=none,has-list-id=yes,d=none) header.from=linuxfoundation.org; iprev=pass policy.iprev=209.132.180.67 (vger.kernel.org); spf=none smtp.mailfrom=stable-owner@vger.kernel.org smtp.helo=vger.kernel.org; x-aligned-from=fail; x-ptr=pass x-ptr-helo=vger.kernel.org x-ptr-lookup=vger.kernel.org; x-return-mx=pass smtp.domain=vger.kernel.org smtp.result=pass smtp_org.domain=kernel.org smtp_org.result=pass smtp_is_org_domain=no header.domain=linuxfoundation.org header.result=pass header_is_org_domain=yes Authentication-Results: mx1.messagingengine.com; arc=none (no signatures found); dkim=none (no signatures found); dmarc=none (p=none,has-list-id=yes,d=none) header.from=linuxfoundation.org; iprev=pass policy.iprev=209.132.180.67 (vger.kernel.org); spf=none smtp.mailfrom=stable-owner@vger.kernel.org smtp.helo=vger.kernel.org; x-aligned-from=fail; x-ptr=pass x-ptr-helo=vger.kernel.org x-ptr-lookup=vger.kernel.org; x-return-mx=pass smtp.domain=vger.kernel.org smtp.result=pass smtp_org.domain=kernel.org smtp_org.result=pass smtp_is_org_domain=no header.domain=linuxfoundation.org header.result=pass header_is_org_domain=yes Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1424974AbeBOPsA (ORCPT ); Thu, 15 Feb 2018 10:48:00 -0500 Received: from mail.linuxfoundation.org ([140.211.169.12]:36398 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1424419AbeBOPr7 (ORCPT ); Thu, 15 Feb 2018 10:47:59 -0500 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Mikulas Patocka , Matt Turner Subject: [PATCH 4.15 168/202] alpha: fix crash if pthread_create races with signal delivery Date: Thu, 15 Feb 2018 16:17:48 +0100 Message-Id: <20180215151721.658590860@linuxfoundation.org> X-Mailer: git-send-email 2.16.1 In-Reply-To: <20180215151712.768794354@linuxfoundation.org> References: <20180215151712.768794354@linuxfoundation.org> User-Agent: quilt/0.65 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: stable-owner@vger.kernel.org X-Mailing-List: stable@vger.kernel.org X-getmail-retrieved-from-mailbox: INBOX X-Mailing-List: linux-kernel@vger.kernel.org List-ID: 4.15-stable review patch. If anyone has any objections, please let me know. ------------------ From: Mikulas Patocka commit 21ffceda1c8b3807615c40d440d7815e0c85d366 upstream. On alpha, a process will crash if it attempts to start a thread and a signal is delivered at the same time. The crash can be reproduced with this program: https://cygwin.com/ml/cygwin/2014-11/msg00473.html The reason for the crash is this: * we call the clone syscall * we go to the function copy_process * copy process calls copy_thread_tls, it is a wrapper around copy_thread * copy_thread sets the tls pointer: childti->pcb.unique = regs->r20 * copy_thread sets regs->r20 to zero * we go back to copy_process * copy process checks "if (signal_pending(current))" and returns -ERESTARTNOINTR * the clone syscall is restarted, but this time, regs->r20 is zero, so the new thread is created with zero tls pointer * the new thread crashes in start_thread when attempting to access tls The comment in the code says that setting the register r20 is some compatibility with OSF/1. But OSF/1 doesn't use the CLONE_SETTLS flag, so we don't have to zero r20 if CLONE_SETTLS is set. This patch fixes the bug by zeroing regs->r20 only if CLONE_SETTLS is not set. Signed-off-by: Mikulas Patocka Signed-off-by: Matt Turner Signed-off-by: Greg Kroah-Hartman --- arch/alpha/kernel/process.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) --- a/arch/alpha/kernel/process.c +++ b/arch/alpha/kernel/process.c @@ -269,12 +269,13 @@ copy_thread(unsigned long clone_flags, u application calling fork. */ if (clone_flags & CLONE_SETTLS) childti->pcb.unique = regs->r20; + else + regs->r20 = 0; /* OSF/1 has some strange fork() semantics. */ childti->pcb.usp = usp ?: rdusp(); *childregs = *regs; childregs->r0 = 0; childregs->r19 = 0; childregs->r20 = 1; /* OSF/1 has some strange fork() semantics. */ - regs->r20 = 0; stack = ((struct switch_stack *) regs) - 1; *childstack = *stack; childstack->r26 = (unsigned long) ret_from_fork;