linux-kernel - [PATCH AUTOSEL 3.18 22/22] mfd: menelaus: Fix possible race condition and leak

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Date:   Wed, 31 Oct 2018 19:12:06 -0400
From:   Sasha Levin <sashal@...nel.org>
To:     stable@...r.kernel.org, linux-kernel@...r.kernel.org
Cc:     Alexandre Belloni <alexandre.belloni@...tlin.com>,
        Lee Jones <lee.jones@...aro.org>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH AUTOSEL 3.18 22/22] mfd: menelaus: Fix possible race condition and leak

From: Alexandre Belloni <alexandre.belloni@...tlin.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@...tlin.com>
Signed-off-by: Lee Jones <lee.jones@...aro.org>
Signed-off-by: Sasha Levin <sashal@...nel.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 9f01aef539dd..8fcb503daae1 100644
--- a/drivers/mfd/menelaus.c
+++ b/drivers/mfd/menelaus.c
@@ -1121,6 +1121,7 @@ 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)) {
@@ -1128,6 +1129,12 @@ 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,
@@ -1152,10 +1159,8 @@ 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