The drm_gem_vunmap() will crash with a NULL dereference if the passed
object pointer is NULL. It wasn't a problem before we added the locking
support to drm_gem_vunmap function because the mapping argument was always
NULL together with the object. Make drm_client_buffer_delete() to check
whether GEM is NULL before trying to unmap the GEM, it will happen on
framebuffer creation error.

Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Link: https://lore.kernel.org/dri-devel/Y1kFEGxT8MVlf32V@kili/
Fixes: 79e2cf2e7a19 ("drm/gem: Take reservation lock for vmap/vunmap operations")
Signed-off-by: Dmitry Osipenko <dmitry.osipenko@collabora.com>
---
 drivers/gpu/drm/drm_client.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/drm_client.c b/drivers/gpu/drm/drm_client.c
index 38e1be991caa..fd67efe37c63 100644
--- a/drivers/gpu/drm/drm_client.c
+++ b/drivers/gpu/drm/drm_client.c
@@ -235,10 +235,10 @@ static void drm_client_buffer_delete(struct drm_client_buffer *buffer)
 {
 	struct drm_device *dev = buffer->client->dev;
 
-	drm_gem_vunmap_unlocked(buffer->gem, &buffer->map);
-
-	if (buffer->gem)
+	if (buffer->gem) {
+		drm_gem_vunmap_unlocked(buffer->gem, &buffer->map);
 		drm_gem_object_put(buffer->gem);
+	}
 
 	if (buffer->handle)
 		drm_mode_destroy_dumb(dev, buffer->handle, buffer->client->file);
-- 
2.37.3

Am 30.10.22 um 16:44 schrieb Dmitry Osipenko:
> The drm_gem_vunmap() will crash with a NULL dereference if the passed
> object pointer is NULL. It wasn't a problem before we added the locking
> support to drm_gem_vunmap function because the mapping argument was always
> NULL together with the object. Make drm_client_buffer_delete() to check
> whether GEM is NULL before trying to unmap the GEM, it will happen on
> framebuffer creation error.
>
> Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
> Link: https://lore.kernel.org/dri-devel/Y1kFEGxT8MVlf32V@kili/
> Fixes: 79e2cf2e7a19 ("drm/gem: Take reservation lock for vmap/vunmap operations")
> Signed-off-by: Dmitry Osipenko <dmitry.osipenko@collabora.com>

Reviewed-by: Christian König <christian.koenig@amd.com>

> ---
>   drivers/gpu/drm/drm_client.c | 6 +++---
>   1 file changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/gpu/drm/drm_client.c b/drivers/gpu/drm/drm_client.c
> index 38e1be991caa..fd67efe37c63 100644
> --- a/drivers/gpu/drm/drm_client.c
> +++ b/drivers/gpu/drm/drm_client.c
> @@ -235,10 +235,10 @@ static void drm_client_buffer_delete(struct drm_client_buffer *buffer)
>   {
>   	struct drm_device *dev = buffer->client->dev;
>   
> -	drm_gem_vunmap_unlocked(buffer->gem, &buffer->map);
> -
> -	if (buffer->gem)
> +	if (buffer->gem) {
> +		drm_gem_vunmap_unlocked(buffer->gem, &buffer->map);
>   		drm_gem_object_put(buffer->gem);
> +	}
>   
>   	if (buffer->handle)
>   		drm_mode_destroy_dumb(dev, buffer->handle, buffer->client->file);

On 11/2/22 12:15, Christian König wrote:
> Am 30.10.22 um 16:44 schrieb Dmitry Osipenko:
>> The drm_gem_vunmap() will crash with a NULL dereference if the passed
>> object pointer is NULL. It wasn't a problem before we added the locking
>> support to drm_gem_vunmap function because the mapping argument was
>> always
>> NULL together with the object. Make drm_client_buffer_delete() to check
>> whether GEM is NULL before trying to unmap the GEM, it will happen on
>> framebuffer creation error.
>>
>> Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
>> Link: https://lore.kernel.org/dri-devel/Y1kFEGxT8MVlf32V@kili/
>> Fixes: 79e2cf2e7a19 ("drm/gem: Take reservation lock for vmap/vunmap
>> operations")
>> Signed-off-by: Dmitry Osipenko <dmitry.osipenko@collabora.com>
> 
> Reviewed-by: Christian König <christian.koenig@amd.com>

Applied to drm-misc-next, thanks!

-- 
Best regards,
Dmitry