[PATCH] drm/vc4: tests: Fix UAF in the mock helpers

[Maíra Canal]

On 10/24/23 07:56, Maxime Ripard wrote:
> The VC4 mock helpers allocate the CRTC, encoders and connectors using a
> call to kunit_kzalloc(), but the DRM device they are attache to survives
> for longer than the test itself which leads to use-after-frees reported
> by KASAN.
> 
> Switch to drmm_kzalloc to tie the lifetime of these objects to the main
> DRM device.
> 
> Fixes: f759f5b53f1c ("drm/vc4: tests: Introduce a mocking infrastructure")
> Closes: https://lore.kernel.org/all/CA+G9fYvJA2HGqzR9LGgq63v0SKaUejHAE6f7+z9cwWN-ourJ_g@mail.gmail.com/
> Reported-by: Linux Kernel Functional Testing <lkft at linaro.org>
> Signed-off-by: Maxime Ripard <mripard at kernel.org>

Reviewed-by: Maíra Canal <mcanal at igalia.com>

Best Regards,
- Maíra Canal

> 
> ---
> 
> Cc: Naresh Kamboju <naresh.kamboju at linaro.org>
> Cc: Dan Carpenter <dan.carpenter at linaro.org>
> ---
>   drivers/gpu/drm/vc4/tests/vc4_mock_crtc.c   | 2 +-
>   drivers/gpu/drm/vc4/tests/vc4_mock_output.c | 2 +-
>   2 files changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/vc4/tests/vc4_mock_crtc.c b/drivers/gpu/drm/vc4/tests/vc4_mock_crtc.c
> index 5d12d7beef0e..ade3309ae042 100644
> --- a/drivers/gpu/drm/vc4/tests/vc4_mock_crtc.c
> +++ b/drivers/gpu/drm/vc4/tests/vc4_mock_crtc.c
> @@ -26,7 +26,7 @@ struct vc4_dummy_crtc *vc4_mock_pv(struct kunit *test,
>   	struct vc4_crtc *vc4_crtc;
>   	int ret;
>   
> -	dummy_crtc = kunit_kzalloc(test, sizeof(*dummy_crtc), GFP_KERNEL);
> +	dummy_crtc = drmm_kzalloc(drm, sizeof(*dummy_crtc), GFP_KERNEL);
>   	KUNIT_ASSERT_NOT_NULL(test, dummy_crtc);
>   
>   	vc4_crtc = &dummy_crtc->crtc;
> diff --git a/drivers/gpu/drm/vc4/tests/vc4_mock_output.c b/drivers/gpu/drm/vc4/tests/vc4_mock_output.c
> index 6e11fcc9ef45..e70d7c3076ac 100644
> --- a/drivers/gpu/drm/vc4/tests/vc4_mock_output.c
> +++ b/drivers/gpu/drm/vc4/tests/vc4_mock_output.c
> @@ -32,7 +32,7 @@ struct vc4_dummy_output *vc4_dummy_output(struct kunit *test,
>   	struct drm_encoder *enc;
>   	int ret;
>   
> -	dummy_output = kunit_kzalloc(test, sizeof(*dummy_output), GFP_KERNEL);
> +	dummy_output = drmm_kzalloc(drm, sizeof(*dummy_output), GFP_KERNEL);
>   	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, dummy_output);
>   	dummy_output->encoder.type = vc4_encoder_type;
>