mfd: menelaus: Fix possible race condition and leak

BugLink: https://bugs.launchpad.net/bugs/1836802
[ Upstream commit 9612f8f503804d2fd2f63aa6ba1e58bba4612d96 ]

The IRQ work is added before the struct rtc is allocated and registered,
but this struct is used in the IRQ handler. This may lead to a NULL pointer
dereference.

Switch to devm_rtc_allocate_device/rtc_register_device to allocate the rtc
before calling menelaus_add_irq_work.

Also, this solves a possible leak as the RTC is never released.

Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Andrea Righi <andrea.righi@canonical.com>
Signed-off-by: Khalid Elmously <khalid.elmously@canonical.com>

diff --git a/drivers/mfd/menelaus.c b/drivers/mfd/menelaus.c
index 29b7164a823bd7d1f81542ae8ec8518ebfd4aad9..d28ebe7ecd211d87c209f6891468cfc55236d046 100644 (file)
--- a/drivers/mfd/menelaus.c
+++ b/drivers/mfd/menelaus.c
@@ -1094,6 +1094,7 @@ static void menelaus_rtc_alarm_work(struct menelaus_chip *m)
 static inline void menelaus_rtc_init(struct menelaus_chip *m)
 {
        int     alarm = (m->client->irq > 0);
+       int     err;
 
        /* assume 32KDETEN pin is pulled high */
        if (!(menelaus_read_reg(MENELAUS_OSC_CTRL) & 0x80)) {
@@ -1101,6 +1102,12 @@ static inline void menelaus_rtc_init(struct menelaus_chip *m)
                return;
        }
 
+       m->rtc = devm_rtc_allocate_device(&m->client->dev);
+       if (IS_ERR(m->rtc))
+               return;
+
+       m->rtc->ops = &menelaus_rtc_ops;
+
        /* support RTC alarm; it can issue wakeups */
        if (alarm) {
                if (menelaus_add_irq_work(MENELAUS_RTCALM_IRQ,
@@ -1125,10 +1132,8 @@ static inline void menelaus_rtc_init(struct menelaus_chip *m)
                menelaus_write_reg(MENELAUS_RTC_CTRL, m->rtc_control);
        }
 
-       m->rtc = rtc_device_register(DRIVER_NAME,
-                       &m->client->dev,
-                       &menelaus_rtc_ops, THIS_MODULE);
-       if (IS_ERR(m->rtc)) {
+       err = rtc_register_device(m->rtc);
+       if (err) {
                if (alarm) {
                        menelaus_remove_irq_work(MENELAUS_RTCALM_IRQ);
                        device_init_wakeup(&m->client->dev, 0);