[PATCH AUTOSEL 4.19 143/146] mfd: menelaus: Fix possible race condition and leak

Sasha Levin
2018-10-31T23:07:53Z

From: Alexandre Belloni <alexandre.belloni@bootlin.com>

[ 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>
---
drivers/mfd/menelaus.c | 13 +++++++++----
1 file changed, 9 insertions(+), 4 deletions(-)

diff --git a/drivers/mfd/menelaus.c b/drivers/mfd/menelaus.c
index 29b7164a823b..d28ebe7ecd21 100644
--- 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);
--
2.17.1