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Message-Id: <20250902112043.3525123-2-aha310510@gmail.com>
Date: Tue, 2 Sep 2025 20:20:41 +0900
From: Jeongjun Park <aha310510@...il.com>
To: inki.dae@...sung.com,
sw0312.kim@...sung.com,
kyungmin.park@...sung.com,
airlied@...il.com,
simona@...ll.ch
Cc: krzk@...nel.org,
alim.akhtar@...sung.com,
dri-devel@...ts.freedesktop.org,
linux-arm-kernel@...ts.infradead.org,
linux-samsung-soc@...r.kernel.org,
linux-kernel@...r.kernel.org,
stable@...r.kernel.org,
aha310510@...il.com
Subject: [PATCH 1/3] drm/exynos: vidi: use priv->vidi_dev for ctx lookup in vidi_connection_ioctl()
vidi_connection_ioctl() retrieves the driver_data from drm_dev->dev to
obtain a struct vidi_context pointer. However, drm_dev->dev is the
exynos-drm master device, and the driver_data contained therein is not
the vidi component device, but a completely different device.
This can lead to various bugs, ranging from null pointer dereferences and
garbage value accesses to, in unlucky cases, out-of-bounds errors,
use-after-free errors, and more.
To resolve this issue, we need to store/delete the vidi device pointer in
exynos_drm_private->vidi_dev during bind/unbind, and then read this
exynos_drm_private->vidi_dev within ioctl() to obtain the correct
struct vidi_context pointer.
Cc: <stable@...r.kernel.org>
Signed-off-by: Jeongjun Park <aha310510@...il.com>
---
drivers/gpu/drm/exynos/exynos_drm_drv.h | 1 +
drivers/gpu/drm/exynos/exynos_drm_vidi.c | 14 +++++++++++++-
2 files changed, 14 insertions(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/exynos/exynos_drm_drv.h b/drivers/gpu/drm/exynos/exynos_drm_drv.h
index 23646e55f142..06c29ff2aac0 100644
--- a/drivers/gpu/drm/exynos/exynos_drm_drv.h
+++ b/drivers/gpu/drm/exynos/exynos_drm_drv.h
@@ -199,6 +199,7 @@ struct drm_exynos_file_private {
struct exynos_drm_private {
struct device *g2d_dev;
struct device *dma_dev;
+ struct device *vidi_dev;
void *mapping;
/* for atomic commit */
diff --git a/drivers/gpu/drm/exynos/exynos_drm_vidi.c b/drivers/gpu/drm/exynos/exynos_drm_vidi.c
index e094b8bbc0f1..1fe297d512e7 100644
--- a/drivers/gpu/drm/exynos/exynos_drm_vidi.c
+++ b/drivers/gpu/drm/exynos/exynos_drm_vidi.c
@@ -223,9 +223,14 @@ ATTRIBUTE_GROUPS(vidi);
int vidi_connection_ioctl(struct drm_device *drm_dev, void *data,
struct drm_file *file_priv)
{
- struct vidi_context *ctx = dev_get_drvdata(drm_dev->dev);
+ struct exynos_drm_private *priv = drm_dev->dev_private;
+ struct device *dev = priv ? priv->vidi_dev : NULL;
+ struct vidi_context *ctx = dev ? dev_get_drvdata(dev) : NULL;
struct drm_exynos_vidi_connection *vidi = data;
+ if (!ctx)
+ return -ENODEV;
+
if (!vidi) {
DRM_DEV_DEBUG_KMS(ctx->dev,
"user data for vidi is null.\n");
@@ -371,6 +376,7 @@ static int vidi_bind(struct device *dev, struct device *master, void *data)
{
struct vidi_context *ctx = dev_get_drvdata(dev);
struct drm_device *drm_dev = data;
+ struct exynos_drm_private *priv = drm_dev->dev_private;
struct drm_encoder *encoder = &ctx->encoder;
struct exynos_drm_plane *exynos_plane;
struct exynos_drm_plane_config plane_config = { 0 };
@@ -378,6 +384,8 @@ static int vidi_bind(struct device *dev, struct device *master, void *data)
int ret;
ctx->drm_dev = drm_dev;
+ if (priv)
+ priv->vidi_dev = dev;
plane_config.pixel_formats = formats;
plane_config.num_pixel_formats = ARRAY_SIZE(formats);
@@ -423,8 +431,12 @@ static int vidi_bind(struct device *dev, struct device *master, void *data)
static void vidi_unbind(struct device *dev, struct device *master, void *data)
{
struct vidi_context *ctx = dev_get_drvdata(dev);
+ struct drm_device *drm_dev = data;
+ struct exynos_drm_private *priv = drm_dev->dev_private;
timer_delete_sync(&ctx->timer);
+ if (priv)
+ priv->vidi_dev = NULL;
}
static const struct component_ops vidi_component_ops = {
--
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