lists.openwall.net   lists  /  announce  owl-users  owl-dev  john-users  john-dev  passwdqc-users  yescrypt  popa3d-users  /  oss-security  kernel-hardening  musl  sabotage  tlsify  passwords  /  crypt-dev  xvendor  /  Bugtraq  Full-Disclosure  linux-kernel  linux-netdev  linux-ext4  linux-hardening  linux-cve-announce  PHC 
Open Source and information security mailing list archives
 
Hash Suite: Windows password security audit tool. GUI, reports in PDF.
[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-Id: <20220107124934.159878-2-mat.jonczyk@o2.pl>
Date:   Fri,  7 Jan 2022 13:49:26 +0100
From:   Mateusz Jończyk <mat.jonczyk@...pl>
To:     linux-rtc@...r.kernel.org, linux-kernel@...r.kernel.org
Cc:     Mateusz Jończyk <mat.jonczyk@...pl>,
        Nobuhiro Iwamatsu <iwamatsu@...auri.org>,
        Alessandro Zummo <a.zummo@...ertech.it>,
        Alexandre Belloni <alexandre.belloni@...tlin.com>,
        stable@...r.kernel.org
Subject: [PATCH v5 1/9] rtc-cmos: take rtc_lock while reading from CMOS

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 <mat.jonczyk@...pl>
Reviewed-by: Nobuhiro Iwamatsu <iwamatsu@...auri.org>
Cc: Alessandro Zummo <a.zummo@...ertech.it>
Cc: Alexandre Belloni <alexandre.belloni@...tlin.com>
Cc: stable@...r.kernel.org
---
 drivers/rtc/rtc-cmos.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/rtc/rtc-cmos.c b/drivers/rtc/rtc-cmos.c
index 4eb53412b808..dc3f8b0dde98 100644
--- a/drivers/rtc/rtc-cmos.c
+++ b/drivers/rtc/rtc-cmos.c
@@ -457,7 +457,10 @@ static int cmos_set_alarm(struct device *dev, struct rtc_wkalrm *t)
 	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;
-- 
2.25.1

Powered by blists - more mailing lists

Powered by Openwall GNU/*/Linux Powered by OpenVZ