linux-kernel - [PATCH 5.15 104/913] rtc: pl031: fix rtc features null pointer dereference

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Date:   Tue,  5 Apr 2022 09:19:26 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Ali Pouladi <quic_apouladi@...cinc.com>,
        Elliot Berman <quic_eberman@...cinc.com>,
        Alexandre Belloni <alexandre.belloni@...tlin.com>
Subject: [PATCH 5.15 104/913] rtc: pl031: fix rtc features null pointer dereference

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

commit ea6af39f3da50c86367a71eb3cc674ade3ed244c upstream.

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>
Signed-off-by: Alexandre Belloni <alexandre.belloni@...tlin.com>
Link: https://lore.kernel.org/r/20220225161924.274141-1-quic_eberman@quicinc.com
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 drivers/rtc/rtc-pl031.c |    6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

--- a/drivers/rtc/rtc-pl031.c
+++ b/drivers/rtc/rtc-pl031.c
@@ -350,9 +350,6 @@ static int pl031_probe(struct amba_devic
 		}
 	}
 
-	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_devic
 		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;