2024-03-28 13:45:16

by Maxim Korotkov

Subject: [PATCH] drm/virtio: add driver_priv validation in virtio_gpu_create_context

The pointer file->driver_priv was dereferenced without checking
against NULL, but in the "virtio_gpu_transfer_to_host_ioctl" function
it was checked against NULL after calling virtio_gpu_create_context
function.

Found by Security Code and Linux Verification Center(linuxtesting.org)
Fixes: 72b48ae800da ("drm/virtio: enqueue virtio_gpu_create_context after the first 3D ioctl")
Signed-off-by: Maxim Korotkov <[email protected]>
---
drivers/gpu/drm/virtio/virtgpu_ioctl.c | 3 +++
1 file changed, 3 insertions(+)

diff --git a/drivers/gpu/drm/virtio/virtgpu_ioctl.c b/drivers/gpu/drm/virtio/virtgpu_ioctl.c
index e4f76f315550..98fe9ad4ed15 100644
--- a/drivers/gpu/drm/virtio/virtgpu_ioctl.c
+++ b/drivers/gpu/drm/virtio/virtgpu_ioctl.c
@@ -64,6 +64,9 @@ void virtio_gpu_create_context(struct drm_device *dev, struct drm_file *file)
struct virtio_gpu_device *vgdev = dev->dev_private;
struct virtio_gpu_fpriv *vfpriv = file->driver_priv;

+ if (!vfpriv)
+ return;
+
mutex_lock(&vfpriv->context_lock);
if (vfpriv->context_created)
goto out_unlock;
--
2.34.1

2024-04-11 12:31:43

by Dmitry Osipenko

Subject: Re: [PATCH] drm/virtio: add driver_priv validation in virtio_gpu_create_context

On 3/28/24 16:43, Maxim Korotkov wrote:
> The pointer file->driver_priv was dereferenced without checking
> against NULL, but in the "virtio_gpu_transfer_to_host_ioctl" function
> it was checked against NULL after calling virtio_gpu_create_context
> function.
>
> Found by Security Code and Linux Verification Center(linuxtesting.org)
> Fixes: 72b48ae800da ("drm/virtio: enqueue virtio_gpu_create_context after the first 3D ioctl")
> Signed-off-by: Maxim Korotkov <[email protected]>
> ---
> drivers/gpu/drm/virtio/virtgpu_ioctl.c | 3 +++
> 1 file changed, 3 insertions(+)
>
> diff --git a/drivers/gpu/drm/virtio/virtgpu_ioctl.c b/drivers/gpu/drm/virtio/virtgpu_ioctl.c
> index e4f76f315550..98fe9ad4ed15 100644
> --- a/drivers/gpu/drm/virtio/virtgpu_ioctl.c
> +++ b/drivers/gpu/drm/virtio/virtgpu_ioctl.c
> @@ -64,6 +64,9 @@ void virtio_gpu_create_context(struct drm_device *dev, struct drm_file *file)
> struct virtio_gpu_device *vgdev = dev->dev_private;
> struct virtio_gpu_fpriv *vfpriv = file->driver_priv;
>
> + if (!vfpriv)
> + return;
> +
> mutex_lock(&vfpriv->context_lock);
> if (vfpriv->context_created)
> goto out_unlock;

NULL check in virtio_gpu_transfer_to_host_ioctl() is bogus, vfpriv can't
be NULL there.

--
Best regards,
Dmitry