From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <linux-kernel-owner@kernel.org>
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 76895C3527E
	for <linux-kernel@archiver.kernel.org>; Tue,  5 Apr 2022 12:02:24 +0000 (UTC)
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
        id S1358903AbiDEL4t (ORCPT
        <rfc822;linux-kernel@archiver.kernel.org>);
        Tue, 5 Apr 2022 07:56:49 -0400
Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46824 "EHLO
        lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org
        with ESMTP id S244945AbiDEIwt (ORCPT
        <rfc822;linux-kernel@vger.kernel.org>);
        Tue, 5 Apr 2022 04:52:49 -0400
Received: from sin.source.kernel.org (sin.source.kernel.org [145.40.73.55])
        by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 4FF4E24BCC;
        Tue,  5 Apr 2022 01:47:21 -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 sin.source.kernel.org (Postfix) with ESMTPS id B4AECCE1C2B;
        Tue,  5 Apr 2022 08:47:19 +0000 (UTC)
Received: by smtp.kernel.org (Postfix) with ESMTPSA id A0B3BC385A1;
        Tue,  5 Apr 2022 08:47:17 +0000 (UTC)
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org;
        s=korg; t=1649148438;
        bh=K3KpOz7kXmndjWfYEJDm29Zc1GUZwo74eJhkKF8o4r4=;
        h=From:To:Cc:Subject:Date:In-Reply-To:References:From;
        b=w7GfMlcAyBqp+LoKfhGpEen+i8BUDPGWC3uwO9A8jUkRXZPuxBhRsOJcrRBfKKDjp
         RUi/Y6Efd/T+4aZZmlvAyv4rp8UDZ84sOGdV+WjslZpldWd+PtBPE3Ukd73y3P6Rlp
         CRMH2KIM7kb3S99YkDt5Hr86Z5QOGoK3SWzCbrJ0=
From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Randy Dunlap <rdunlap@infradead.org>,
        Igor Zhbanov <i.zhbanov@omprussia.ru>,
        Borislav Petkov <bp@suse.de>,
        Andrew Morton <akpm@linux-foundation.org>,
        Petr Mladek <pmladek@suse.com>,
        Sergey Senozhatsky <senozhatsky@chromium.org>,
        Steven Rostedt <rostedt@goodmis.org>,
        John Ogness <john.ogness@linutronix.de>,
        Sasha Levin <sashal@kernel.org>
Subject: [PATCH 5.16 0358/1017] printk: fix return value of printk.devkmsg __setup handler
Date:   Tue,  5 Apr 2022 09:21:11 +0200
Message-Id: <20220405070404.912052325@linuxfoundation.org>
X-Mailer: git-send-email 2.35.1
In-Reply-To: <20220405070354.155796697@linuxfoundation.org>
References: <20220405070354.155796697@linuxfoundation.org>
User-Agent: quilt/0.66
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
Precedence: bulk
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

From: Randy Dunlap <rdunlap@infradead.org>

[ Upstream commit b665eae7a788c5e2bc10f9ac3c0137aa0ad1fc97 ]

If an invalid option value is used with "printk.devkmsg=<value>",
it is silently ignored.
If a valid option value is used, it is honored but the wrong return
value (0) is used, indicating that the command line option had an
error and was not handled. This string is not added to init's
environment strings due to init/main.c::unknown_bootoption()
checking for a '.' in the boot option string and then considering
that string to be an "Unused module parameter".

Print a warning message if a bad option string is used.
Always return 1 from the __setup handler to indicate that the command
line option has been handled.

Fixes: 750afe7babd1 ("printk: add kernel parameter to control writes to /dev/kmsg")
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Reported-by: Igor Zhbanov <i.zhbanov@omprussia.ru>
Link: lore.kernel.org/r/64644a2f-4a20-bab3-1e15-3b2cdd0defe3@omprussia.ru
Cc: Borislav Petkov <bp@suse.de>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Petr Mladek <pmladek@suse.com>
Cc: Sergey Senozhatsky <senozhatsky@chromium.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: John Ogness <john.ogness@linutronix.de>
Reviewed-by: John Ogness <john.ogness@linutronix.de>
Reviewed-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Signed-off-by: Petr Mladek <pmladek@suse.com>
Link: https://lore.kernel.org/r/20220228220556.23484-1-rdunlap@infradead.org
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 kernel/printk/printk.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
index 57b132b658e1..4187946a28f9 100644
--- a/kernel/printk/printk.c
+++ b/kernel/printk/printk.c
@@ -146,8 +146,10 @@ static int __control_devkmsg(char *str)
 
 static int __init control_devkmsg(char *str)
 {
-	if (__control_devkmsg(str) < 0)
+	if (__control_devkmsg(str) < 0) {
+		pr_warn("printk.devkmsg: bad option string '%s'\n", str);
 		return 1;
+	}
 
 	/*
 	 * Set sysctl string accordingly:
@@ -166,7 +168,7 @@ static int __init control_devkmsg(char *str)
 	 */
 	devkmsg_log |= DEVKMSG_LOG_MASK_LOCK;
 
-	return 0;
+	return 1;
 }
 __setup("printk.devkmsg=", control_devkmsg);
 
-- 
2.34.1