From patchwork Tue Jan 24 18:51:10 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Eric Biggers X-Patchwork-Id: 13114577 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 10967C54E94 for ; Tue, 24 Jan 2023 18:53:03 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234480AbjAXSxA (ORCPT ); Tue, 24 Jan 2023 13:53:00 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56774 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233981AbjAXSwj (ORCPT ); Tue, 24 Jan 2023 13:52:39 -0500 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 9B52146710; Tue, 24 Jan 2023 10:52:14 -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 0F95E60FAC; Tue, 24 Jan 2023 18:52:14 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 52190C433A7; Tue, 24 Jan 2023 18:52:13 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1674586333; bh=7ngLw52uUuani2uGj/8r6J5RH0dFgQRDLQLIbTIDHD8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=tUUF4HO0FNK4sz9CZ3F4mBiXTNgy1UdkI6zgY8CbI3wY+2gwR5fJ85AumMBiMUKgV ZIQ3T9R1iLa5I9K2FCd84av0NvzxK85XhgDocEAphce7ErWMHLsvjj+7k6Xt4wG2kY SCSL5p22EEeor6T1zMYJJbENdsTDQvtIqByihx3vPKzChoLT/c6qLSDWz8gaeoNX17 X2/FJqR0iwt1FggsdIh6lJmlUp0AL2vaMtsAXbI0BM7KmzcLhMbcdFW9Un6aW/m9iv JZGrnf9Y6CtMMnEQjbw9N+ZHHJlgXR7RXFXqshmJiOu8evdzKKHaac/Vo2i1aiwrP3 OopGxQoFazbaQ== From: Eric Biggers To: stable@vger.kernel.org, Greg Kroah-Hartman Cc: Kees Cook , SeongJae Park , Seth Jenkins , Jann Horn , "Eric W . Biederman" , linux-hardening@vger.kernel.org, linux-kernel@vger.kernel.org, Arnd Bergmann , Petr Mladek , Andrew Morton , Luis Chamberlain , Marco Elver , tangmeng , Sebastian Andrzej Siewior , Tiezhu Yang , Peter Zijlstra Subject: [PATCH 5.15 20/20] exit: Use READ_ONCE() for all oops/warn limit reads Date: Tue, 24 Jan 2023 10:51:10 -0800 Message-Id: <20230124185110.143857-21-ebiggers@kernel.org> X-Mailer: git-send-email 2.39.1 In-Reply-To: <20230124185110.143857-1-ebiggers@kernel.org> References: <20230124185110.143857-1-ebiggers@kernel.org> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-hardening@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 --- 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 f6c85101dba0f..80efdfda6662b 100644 --- a/kernel/exit.c +++ b/kernel/exit.c @@ -930,6 +930,7 @@ 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 @@ -941,8 +942,9 @@ 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 4aef355e9a5d1..47933d4c769b6 100644 --- a/kernel/panic.c +++ b/kernel/panic.c @@ -223,12 +223,15 @@ 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); } /**