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 ACED3C6379F for ; Fri, 3 Feb 2023 10:33:37 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233049AbjBCKdg (ORCPT ); Fri, 3 Feb 2023 05:33:36 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57836 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233346AbjBCKdC (ORCPT ); Fri, 3 Feb 2023 05:33:02 -0500 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A1F1AA429D for ; Fri, 3 Feb 2023 02:31:27 -0800 (PST) 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 1C6EA61E93 for ; Fri, 3 Feb 2023 10:31:27 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id D127BC433EF; Fri, 3 Feb 2023 10:31:25 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1675420286; bh=80EA5XDWw49pqWbW9IyD/pBb5C7mSCaxCZzNh3UQ1wI=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Nx+wSElBwl8Le9k/AQaaOGURe3G7BQWZ6Ja14QECBLGQtCYVw6Wamtt7plmFLGs2Y T8/uT/6E5IonHxSfgm5/uz2gWLLrIk0XnLqN1jckb41z/t7lGD26bXuu3VGfFSydR6 +qM8JmcP0WRKnR+Y+AA/vpS3WGdcDU3zfo7x1Jq8= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Peter Zijlstra , "Eric W. Biederman" , Jann Horn , Arnd Bergmann , Petr Mladek , Andrew Morton , Luis Chamberlain , Marco Elver , tangmeng , Sebastian Andrzej Siewior , Tiezhu Yang , Kees Cook , Eric Biggers , Sasha Levin Subject: [PATCH 5.4 130/134] exit: Use READ_ONCE() for all oops/warn limit reads Date: Fri, 3 Feb 2023 11:13:55 +0100 Message-Id: <20230203101029.670751446@linuxfoundation.org> X-Mailer: git-send-email 2.39.1 In-Reply-To: <20230203101023.832083974@linuxfoundation.org> References: <20230203101023.832083974@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: stable@vger.kernel.org From: Kees Cook commit 7535b832c6399b5ebfc5b53af5c51dd915ee2538 upstream. Use a temporary variable to take full advantage of READ_ONCE() behavior. Without this, the report (and even the test) might be out of sync with the initial test. Reported-by: Peter Zijlstra Link: https://lore.kernel.org/lkml/Y5x7GXeluFmZ8E0E@hirez.programming.kicks-ass.net Fixes: 9fc9e278a5c0 ("panic: Introduce warn_limit") Fixes: d4ccd54d28d3 ("exit: Put an upper limit on how often we can oops") Cc: "Eric W. Biederman" Cc: Jann Horn Cc: Arnd Bergmann Cc: Petr Mladek Cc: Andrew Morton Cc: Luis Chamberlain Cc: Marco Elver Cc: tangmeng Cc: Sebastian Andrzej Siewior Cc: Tiezhu Yang Signed-off-by: Kees Cook Signed-off-by: Eric Biggers Signed-off-by: Sasha Levin --- kernel/exit.c | 6 ++++-- kernel/panic.c | 7 +++++-- 2 files changed, 9 insertions(+), 4 deletions(-) diff --git a/kernel/exit.c b/kernel/exit.c index 381282fb756c..563bdaa76694 100644 --- a/kernel/exit.c +++ b/kernel/exit.c @@ -917,6 +917,7 @@ void __noreturn make_task_dead(int signr) * Take the task off the cpu after something catastrophic has * happened. */ + unsigned int limit; /* * Every time the system oopses, if the oops happens while a reference @@ -928,8 +929,9 @@ void __noreturn make_task_dead(int signr) * To make sure this can't happen, place an upper bound on how often the * kernel may oops without panic(). */ - if (atomic_inc_return(&oops_count) >= READ_ONCE(oops_limit) && oops_limit) - panic("Oopsed too often (kernel.oops_limit is %d)", oops_limit); + limit = READ_ONCE(oops_limit); + if (atomic_inc_return(&oops_count) >= limit && limit) + panic("Oopsed too often (kernel.oops_limit is %d)", limit); do_exit(signr); } diff --git a/kernel/panic.c b/kernel/panic.c index 2c118645e740..cef79466f941 100644 --- a/kernel/panic.c +++ b/kernel/panic.c @@ -199,12 +199,15 @@ static void panic_print_sys_info(void) void check_panic_on_warn(const char *origin) { + unsigned int limit; + if (panic_on_warn) panic("%s: panic_on_warn set ...\n", origin); - if (atomic_inc_return(&warn_count) >= READ_ONCE(warn_limit) && warn_limit) + limit = READ_ONCE(warn_limit); + if (atomic_inc_return(&warn_count) >= limit && limit) panic("%s: system warned too often (kernel.warn_limit is %d)", - origin, warn_limit); + origin, limit); } /** -- 2.39.0