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 B0597C433F5 for ; Mon, 24 Jan 2022 18:52:07 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1343555AbiAXSwG (ORCPT ); Mon, 24 Jan 2022 13:52:06 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43270 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1343598AbiAXSvG (ORCPT ); Mon, 24 Jan 2022 13:51:06 -0500 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D62ECC061797; Mon, 24 Jan 2022 10:50:44 -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 ams.source.kernel.org (Postfix) with ESMTPS id 93094B810BD; Mon, 24 Jan 2022 18:50:43 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id B3126C340E5; Mon, 24 Jan 2022 18:50:41 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1643050242; bh=Z61lJENDMxEpYURPDCUWyB6NKwLICZ+bTHmh4lU0xC4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Mm5wWVaFtotYrn1GrH9QTS3Gn3r/gGW8UtZGroTdWIYaUjdaLyvIVvMJeRB9QmOPQ jbG/w5scnhyvpYg5XU2dGffDRWbTcgHqbRQ4Io+Jl94dqZrQiBp1hb540m1qGbs+Jn Z0phDjooTHfzIvs1tjoqeyDXvSAcjtxUK2BwyzQM= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, =?UTF-8?q?Mateusz=20Jo=C5=84czyk?= , Nobuhiro Iwamatsu , Alessandro Zummo , Alexandre Belloni Subject: [PATCH 4.4 012/114] rtc: cmos: take rtc_lock while reading from CMOS Date: Mon, 24 Jan 2022 19:41:47 +0100 Message-Id: <20220124183927.492636970@linuxfoundation.org> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20220124183927.095545464@linuxfoundation.org> References: <20220124183927.095545464@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: X-Mailing-List: stable@vger.kernel.org From: Mateusz Jończyk commit 454f47ff464325223129b9b5b8d0b61946ec704d upstream. Reading from the CMOS involves writing to the index register and then reading from the data register. Therefore access to the CMOS has to be serialized with rtc_lock. This invocation of CMOS_READ was not serialized, which could cause trouble when other code is accessing CMOS at the same time. Use spin_lock_irq() like the rest of the function. Nothing in kernel modifies the RTC_DM_BINARY bit, so there could be a separate pair of spin_lock_irq() / spin_unlock_irq() before doing the math. Signed-off-by: Mateusz Jończyk Reviewed-by: Nobuhiro Iwamatsu Cc: Alessandro Zummo Cc: Alexandre Belloni Cc: stable@vger.kernel.org Signed-off-by: Alexandre Belloni Link: https://lore.kernel.org/r/20211210200131.153887-2-mat.jonczyk@o2.pl Signed-off-by: Greg Kroah-Hartman --- drivers/rtc/rtc-cmos.c | 3 +++ 1 file changed, 3 insertions(+) --- a/drivers/rtc/rtc-cmos.c +++ b/drivers/rtc/rtc-cmos.c @@ -343,7 +343,10 @@ static int cmos_set_alarm(struct device min = t->time.tm_min; sec = t->time.tm_sec; + spin_lock_irq(&rtc_lock); rtc_control = CMOS_READ(RTC_CONTROL); + spin_unlock_irq(&rtc_lock); + if (!(rtc_control & RTC_DM_BINARY) || RTC_ALWAYS_BCD) { /* Writing 0xff means "don't care" or "match all". */ mon = (mon <= 12) ? bin2bcd(mon) : 0xff;