linux-kernel - [PATCH v1 2/2] drm/sprd: fix potential NULL dereference

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Date:   Fri, 24 Dec 2021 22:12:13 +0800
From:   Kevin Tang <kevin3.tang@...il.com>
To:     maarten.lankhorst@...ux.intel.com, mripard@...nel.org,
        sean@...rly.run, airlied@...ux.ie, daniel@...ll.ch,
        robh+dt@...nel.org, mark.rutland@....com
Cc:     kevin3.tang@...il.com, pony1.wu@...il.com, orsonzhai@...il.com,
        dan.carpenter@...cle.com, zou_wei@...wei.com,
        lukas.bulwahn@...il.com, zhang.lyra@...il.com,
        linux-kernel@...r.kernel.org, dri-devel@...ts.freedesktop.org,
        devicetree@...r.kernel.org
Subject: [PATCH v1 2/2] drm/sprd: fix potential NULL dereference

platform_get_resource() may fail and return NULL, so check it's value
before using it.

'drm' could be null in sprd_drm_shutdown, and drm_warn maybe dereference
it, remove this warning log.

Cc: Orson Zhai <orsonzhai@...il.com>
Cc: Chunyan Zhang <zhang.lyra@...il.com>
Signed-off-by: Kevin Tang <kevin.tang@...soc.com>
---
 drivers/gpu/drm/sprd/sprd_dpu.c | 3 +++
 drivers/gpu/drm/sprd/sprd_drm.c | 8 ++------
 drivers/gpu/drm/sprd/sprd_dsi.c | 3 +++
 3 files changed, 8 insertions(+), 6 deletions(-)

diff --git a/drivers/gpu/drm/sprd/sprd_dpu.c b/drivers/gpu/drm/sprd/sprd_dpu.c
index 06a3414ee..69683b7ba 100644
--- a/drivers/gpu/drm/sprd/sprd_dpu.c
+++ b/drivers/gpu/drm/sprd/sprd_dpu.c
@@ -790,6 +790,9 @@ static int sprd_dpu_context_init(struct sprd_dpu *dpu,
 	int ret;
 
 	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	if (!res)
+		return -EINVAL;
+
 	ctx->base = devm_ioremap(dev, res->start, resource_size(res));
 	if (!ctx->base) {
 		dev_err(dev, "failed to map dpu registers\n");
diff --git a/drivers/gpu/drm/sprd/sprd_drm.c b/drivers/gpu/drm/sprd/sprd_drm.c
index a077e2d4d..54030839e 100644
--- a/drivers/gpu/drm/sprd/sprd_drm.c
+++ b/drivers/gpu/drm/sprd/sprd_drm.c
@@ -154,12 +154,8 @@ static void sprd_drm_shutdown(struct platform_device *pdev)
 {
 	struct drm_device *drm = platform_get_drvdata(pdev);
 
-	if (!drm) {
-		drm_warn(drm, "drm device is not available, no shutdown\n");
-		return;
-	}
-
-	drm_atomic_helper_shutdown(drm);
+	if (drm)
+		drm_atomic_helper_shutdown(drm);
 }
 
 static const struct of_device_id drm_match_table[] = {
diff --git a/drivers/gpu/drm/sprd/sprd_dsi.c b/drivers/gpu/drm/sprd/sprd_dsi.c
index 911b3cddc..955c5995a 100644
--- a/drivers/gpu/drm/sprd/sprd_dsi.c
+++ b/drivers/gpu/drm/sprd/sprd_dsi.c
@@ -907,6 +907,9 @@ static int sprd_dsi_context_init(struct sprd_dsi *dsi,
 	struct resource *res;
 
 	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	if (!res)
+		return -EINVAL;
+
 	ctx->base = devm_ioremap(dev, res->start, resource_size(res));
 	if (!ctx->base) {
 		drm_err(dsi->drm, "failed to map dsi host registers\n");
-- 
2.29.0