linux-kernel - [PATCH] rtc: pl031: fix rtc features null pointer dereference

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Date:   Fri, 25 Feb 2022 08:19:24 -0800
From:   Elliot Berman <quic_eberman@...cinc.com>
To:     Linus Walleij <linus.walleij@...aro.org>,
        Alessandro Zummo <a.zummo@...ertech.it>,
        Alexandre Belloni <alexandre.belloni@...tlin.com>
CC:     Ali Pouladi <quic_apouladi@...cinc.com>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-rtc@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        Carl van Schaik <quic_cvanscha@...cinc.com>,
        <stable@...r.kernel.org>, Elliot Berman <quic_eberman@...cinc.com>
Subject: [PATCH] rtc: pl031: fix rtc features null pointer dereference

From: Ali Pouladi <quic_apouladi@...cinc.com>

When there is no interrupt line, rtc alarm feature is disabled.

The clearing of the alarm feature bit was being done prior to allocations
of ldata->rtc device, resulting in a null pointer dereference.

Clear RTC_FEATURE_ALARM after the rtc device is allocated.

Fixes: d9b0dd54a194 ("rtc: pl031: use RTC_FEATURE_ALARM")
Cc: stable@...r.kernel.org
Signed-off-by: Ali Pouladi <quic_apouladi@...cinc.com>
Signed-off-by: Elliot Berman <quic_eberman@...cinc.com>
---
 drivers/rtc/rtc-pl031.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/rtc/rtc-pl031.c b/drivers/rtc/rtc-pl031.c
index e38ee8848385..bad6a5d9c683 100644
--- a/drivers/rtc/rtc-pl031.c
+++ b/drivers/rtc/rtc-pl031.c
@@ -350,9 +350,6 @@ static int pl031_probe(struct amba_device *adev, const struct amba_id *id)
 		}
 	}
 
-	if (!adev->irq[0])
-		clear_bit(RTC_FEATURE_ALARM, ldata->rtc->features);
-
 	device_init_wakeup(&adev->dev, true);
 	ldata->rtc = devm_rtc_allocate_device(&adev->dev);
 	if (IS_ERR(ldata->rtc)) {
@@ -360,6 +357,9 @@ static int pl031_probe(struct amba_device *adev, const struct amba_id *id)
 		goto out;
 	}
 
+	if (!adev->irq[0])
+		clear_bit(RTC_FEATURE_ALARM, ldata->rtc->features);
+
 	ldata->rtc->ops = ops;
 	ldata->rtc->range_min = vendor->range_min;
 	ldata->rtc->range_max = vendor->range_max;
-- 
2.25.1