Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org,
        Alexandre Belloni <alexandre.belloni@bootlin.com>,
        Sasha Levin <sashal@kernel.org>
Subject: [PATCH 4.19 199/276] rtc: xgene: fix possible race condition
Date:   Wed, 29 May 2019 20:05:57 -0700
Message-Id: <20190530030537.555698648@linuxfoundation.org>
In-Reply-To: <20190530030523.133519668@linuxfoundation.org>
References: <20190530030523.133519668@linuxfoundation.org>
User-Agent: quilt/0.66
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

[ Upstream commit a652e00ee1233e251a337c28e18a1da59224e5ce ]

The IRQ is requested 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
struct before requesting the IRQ.

Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/rtc/rtc-xgene.c | 18 +++++++++++-------
 1 file changed, 11 insertions(+), 7 deletions(-)

diff --git a/drivers/rtc/rtc-xgene.c b/drivers/rtc/rtc-xgene.c
index 153820876a820..2f741f455c30a 100644
--- a/drivers/rtc/rtc-xgene.c
+++ b/drivers/rtc/rtc-xgene.c
@@ -168,6 +168,10 @@ static int xgene_rtc_probe(struct platform_device *pdev)
 	if (IS_ERR(pdata->csr_base))
 		return PTR_ERR(pdata->csr_base);
 
+	pdata->rtc = devm_rtc_allocate_device(&pdev->dev);
+	if (IS_ERR(pdata->rtc))
+		return PTR_ERR(pdata->rtc);
+
 	irq = platform_get_irq(pdev, 0);
 	if (irq < 0) {
 		dev_err(&pdev->dev, "No IRQ resource\n");
@@ -198,15 +202,15 @@ static int xgene_rtc_probe(struct platform_device *pdev)
 		return ret;
 	}
 
-	pdata->rtc = devm_rtc_device_register(&pdev->dev, pdev->name,
-					 &xgene_rtc_ops, THIS_MODULE);
-	if (IS_ERR(pdata->rtc)) {
-		clk_disable_unprepare(pdata->clk);
-		return PTR_ERR(pdata->rtc);
-	}
-
 	/* HW does not support update faster than 1 seconds */
 	pdata->rtc->uie_unsupported = 1;
+	pdata->rtc->ops = &xgene_rtc_ops;
+
+	ret = rtc_register_device(pdata->rtc);
+	if (ret) {
+		clk_disable_unprepare(pdata->clk);
+		return ret;
+	}
 
 	return 0;
 }
-- 
2.20.1