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@vger.kernel.org Signed-off-by: Jeongjun Park aha310510@gmail.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 = { --