Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
From:   Sasha Levin <sashal@kernel.org>
To:     linux-kernel@vger.kernel.org, stable@vger.kernel.org
Cc:     Alexandre Belloni <alexandre.belloni@bootlin.com>,
        Sasha Levin <sashal@kernel.org>, rtc-linux@googlegroups.com
Subject: [PATCH AUTOSEL 5.4 176/330] rtc: ds1374: fix possible race condition
Date:   Thu, 17 Sep 2020 21:58:36 -0400
Message-Id: <20200918020110.2063155-176-sashal@kernel.org>
In-Reply-To: <20200918020110.2063155-1-sashal@kernel.org>
References: <20200918020110.2063155-1-sashal@kernel.org>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Precedence: bulk

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

[ Upstream commit c11af8131a4e7ba1960faed731ee7e84c2c13c94 ]

The RTC IRQ is requested before the struct rtc_device is allocated,
this may lead to a NULL pointer dereference in the IRQ handler.

To fix this issue, allocating the rtc_device struct before requesting
the RTC IRQ using devm_rtc_allocate_device, and use rtc_register_device
to register the RTC device.

Link: https://lore.kernel.org/r/20200306073404.56921-1-alexandre.belloni@bootlin.com
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/rtc/rtc-ds1374.c | 15 +++++++++------
 1 file changed, 9 insertions(+), 6 deletions(-)

diff --git a/drivers/rtc/rtc-ds1374.c b/drivers/rtc/rtc-ds1374.c
index 367497914c100..28eb96cbaf98b 100644
--- a/drivers/rtc/rtc-ds1374.c
+++ b/drivers/rtc/rtc-ds1374.c
@@ -620,6 +620,10 @@ static int ds1374_probe(struct i2c_client *client,
 	if (!ds1374)
 		return -ENOMEM;
 
+	ds1374->rtc = devm_rtc_allocate_device(&client->dev);
+	if (IS_ERR(ds1374->rtc))
+		return PTR_ERR(ds1374->rtc);
+
 	ds1374->client = client;
 	i2c_set_clientdata(client, ds1374);
 
@@ -641,12 +645,11 @@ static int ds1374_probe(struct i2c_client *client,
 		device_set_wakeup_capable(&client->dev, 1);
 	}
 
-	ds1374->rtc = devm_rtc_device_register(&client->dev, client->name,
-						&ds1374_rtc_ops, THIS_MODULE);
-	if (IS_ERR(ds1374->rtc)) {
-		dev_err(&client->dev, "unable to register the class device\n");
-		return PTR_ERR(ds1374->rtc);
-	}
+	ds1374->rtc->ops = &ds1374_rtc_ops;
+
+	ret = rtc_register_device(ds1374->rtc);
+	if (ret)
+		return ret;
 
 #ifdef CONFIG_RTC_DRV_DS1374_WDT
 	save_client = client;
-- 
2.25.1