linux-kernel - [PATCH v2] reset: hisilicon: fix potential NULL pointer dereference

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Date:   Wed, 25 Jul 2018 19:47:19 -0500
From:   "Gustavo A. R. Silva" <gustavo@...eddedor.com>
To:     Michael Turquette <mturquette@...libre.com>,
        Stephen Boyd <sboyd@...nel.org>,
        Jiancheng Xue <xuejiancheng@...ilicon.com>
Cc:     linux-clk@...r.kernel.org, linux-kernel@...r.kernel.org,
        "Gustavo A. R. Silva" <gustavo@...eddedor.com>
Subject: [PATCH v2] reset: hisilicon: fix potential NULL pointer dereference

There is a potential execution path in which function
platform_get_resource() returns NULL. If this happens,
we will end up having a NULL pointer dereference.

Fix this by replacing devm_ioremap with devm_ioremap_resource,
which has the NULL check and the memory region request.

This code was detected with the help of Coccinelle.

Cc: stable@...r.kernel.org
Fixes: 97b7129cd2af ("reset: hisilicon: change the definition of hisi_reset_init")
Signed-off-by: Gustavo A. R. Silva <gustavo@...eddedor.com>
---
Changes in v2:
 - Use devm_ioremap_resource. Thanks to Stephen Boyd for
   pointing it out.

 drivers/clk/hisilicon/reset.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/drivers/clk/hisilicon/reset.c b/drivers/clk/hisilicon/reset.c
index 2a5015c..43e82fa 100644
--- a/drivers/clk/hisilicon/reset.c
+++ b/drivers/clk/hisilicon/reset.c
@@ -109,9 +109,8 @@ struct hisi_reset_controller *hisi_reset_init(struct platform_device *pdev)
 		return NULL;
 
 	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
-	rstc->membase = devm_ioremap(&pdev->dev,
-				res->start, resource_size(res));
-	if (!rstc->membase)
+	rstc->membase = devm_ioremap_resource(&pdev->dev, res);
+	if (IS_ERR(rstc->membase))
 		return NULL;
 
 	spin_lock_init(&rstc->lock);
-- 
2.7.4