linux-kernel - [PATCH -next] drm/meson: Fix potential NULL dereference in meson_drv_bind

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Date:   Tue, 20 Mar 2018 14:20:30 +0000
From:   Wei Yongjun <weiyongjun1@...wei.com>
To:     Neil Armstrong <narmstrong@...libre.com>,
        David Airlie <airlied@...ux.ie>,
        Carlo Caione <carlo@...one.org>,
        Kevin Hilman <khilman@...libre.com>
CC:     Wei Yongjun <weiyongjun1@...wei.com>,
        <dri-devel@...ts.freedesktop.org>,
        <linux-amlogic@...ts.infradead.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>, <kernel-janitors@...r.kernel.org>
Subject: [PATCH -next] drm/meson: Fix potential NULL dereference in meson_drv_bind_master()

platform_get_resource_byname() may fail and return NULL, so we should
better check it's return value to avoid a NULL pointer dereference
a bit later in the code.

This is detected by Coccinelle semantic patch.

@@
expression pdev, res, n, t, e, e1, e2;
@@

res = platform_get_resource_byname(pdev, t, n);
+ if (!res)
+   return -EINVAL;
... when != res == NULL
e = devm_ioremap(e1, res->start, e2);

Signed-off-by: Wei Yongjun <weiyongjun1@...wei.com>
---
 drivers/gpu/drm/meson/meson_drv.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/gpu/drm/meson/meson_drv.c b/drivers/gpu/drm/meson/meson_drv.c
index 3baceb7..32b1a6c 100644
--- a/drivers/gpu/drm/meson/meson_drv.c
+++ b/drivers/gpu/drm/meson/meson_drv.c
@@ -197,6 +197,8 @@ static int meson_drv_bind_master(struct device *dev, bool has_components)
 	priv->io_base = regs;
 
 	res = platform_get_resource_byname(pdev, IORESOURCE_MEM, "hhi");
+	if (!res)
+		return -EINVAL;
 	/* Simply ioremap since it may be a shared register zone */
 	regs = devm_ioremap(dev, res->start, resource_size(res));
 	if (!regs) {
@@ -213,6 +215,8 @@ static int meson_drv_bind_master(struct device *dev, bool has_components)
 	}
 
 	res = platform_get_resource_byname(pdev, IORESOURCE_MEM, "dmc");
+	if (!res)
+		return -EINVAL;
 	/* Simply ioremap since it may be a shared register zone */
 	regs = devm_ioremap(dev, res->start, resource_size(res));
 	if (!regs) {