Re: [PATCH] drm/amd/display: Fix use-after-free bugs in KUnit tests

On 7/24/26 14:36, Alex Hung wrote:
> On 7/24/26 15:09, John Harrison wrote:
>> On 7/24/26 12:37, Alex Hung wrote:
>>> Reviewed-by: Alex Hung <[email protected]>
>>>
>>> With two comments:
>>> 1. There is a minor conflicts on include
>>> 2. The following code seems to have the same patterns (passing to 
>>> drmm_* functions). Do they need to be changed too?
>> None of those functions exist in my tree. Which might also explain 
>> the include conflict. I'm using drm-tip fetched the same day I posted 
>> the patch. Should I be basing the patch on a different tree?
>
> My bad. My local branch contains additional patches.
>
> I will create a patch for this four additional changes. Thanks for 
> pointing this out.
Can this patch be merged? It would be good to get the existing issues fixed.

Thanks,
John.

>
>>
>> John.
>>
>>
>>>
>>>
>>> --- drivers/gpu/drm/amd/display/amdgpu_dm/tests/ 
>>> amdgpu_dm_connector_test.c
>>> +++ drivers/gpu/drm/amd/display/amdgpu_dm/tests/ 
>>> amdgpu_dm_connector_test.c
>>> @@ -3645,7 +3645,7 @@ static struct dm_test_stream_ctx 
>>> *dm_test_stream_ctx_alloc(struct kunit *test)
>>> DRIVER_MODESET);
>>>         KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ctx->drm);
>>>
>>> -       ctx->aconnector = kunit_kzalloc(test, sizeof(*ctx- 
>>> >aconnector), GFP_KERNEL);
>>> +       ctx->aconnector = drmm_kzalloc(ctx->drm, sizeof(*ctx- 
>>> >aconnector), GFP_KERNEL);
>>>         KUNIT_ASSERT_NOT_NULL(test, ctx->aconnector);
>>>         KUNIT_ASSERT_EQ(test,
>>>                 drmm_connector_init(ctx->drm, &ctx->aconnector->base,
>>> @@ -3903,7 +3903,7 @@ static void 
>>> dm_test_poll_dac_load_returns_cached(struct kunit *test)
>>>         KUNIT_ASSERT_NOT_ERR_OR_NULL(test, drm);
>>>         adev = drm_to_adev(drm);
>>>
>>> -       aconnector = kunit_kzalloc(test, sizeof(*aconnector), 
>>> GFP_KERNEL);
>>> +       aconnector = drmm_kzalloc(drm, sizeof(*aconnector), 
>>> GFP_KERNEL);
>>>         KUNIT_ASSERT_NOT_NULL(test, aconnector);
>>>         KUNIT_ASSERT_EQ(test,
>>>                 drmm_connector_init(drm, &aconnector->base,
>>> @@ -3950,7 +3950,7 @@ static struct amdgpu_dm_connector 
>>> *dm_test_reg_connector(struct kunit *test)
>>> DRIVER_MODESET);
>>>         KUNIT_ASSERT_NOT_ERR_OR_NULL(test, drm);
>>>
>>> -       aconnector = kunit_kzalloc(test, sizeof(*aconnector), 
>>> GFP_KERNEL);
>>> +       aconnector = drmm_kzalloc(drm, sizeof(*aconnector), 
>>> GFP_KERNEL);
>>>         KUNIT_ASSERT_NOT_NULL(test, aconnector);
>>>         KUNIT_ASSERT_EQ(test,
>>>                 drmm_connector_init(drm, &aconnector->base,
>>> @@ -4405,7 +4405,7 @@ dm_test_modes_ctx_alloc(struct kunit *test, 
>>> int connector_type)
>>>         ctx->drm = dm_test_alloc_drm(test);
>>>         ctx->aconnector = dm_test_add_connector(test, ctx->drm, 
>>> connector_type);
>>>
>>> -       ctx->aenc = kunit_kzalloc(test, sizeof(*ctx->aenc), 
>>> GFP_KERNEL);
>>> +       ctx->aenc = drmm_kzalloc(ctx->drm, sizeof(*ctx->aenc), 
>>> GFP_KERNEL);
>>>         KUNIT_ASSERT_NOT_NULL(test, ctx->aenc);
>>>         KUNIT_ASSERT_EQ(test,
>>>                         drmm_encoder_init(ctx->drm, 
>>> &ctx->aenc->base, NULL,
>>>
>>>
>>> On 7/23/26 17:35, John Harrison wrote:
>>>> When running the KUnit tests with memory debugging enabled, a bunch of
>>>> use-after-free errors are hit. These are due to using KUnit managed
>>>> memory for the test objects but then giving them over to DRM managed
>>>> objects. The KUnit stuff is deallocated first and when the DRM side
>>>> calls its clean up helpers, it hits memory that has been freed 
>>>> already.
>>>>
>>>> NB: There is still a use-after-free bug in the writeback tests.
>>>> However, fixing that requires driver side changes as well as test side
>>>> changes. Those changes are part of:
>>>>    https://patchwork.freedesktop.org/series/152420/
>>>>
>>>> Signed-off-by: John Harrison <[email protected]>
>>>> CC: Alex Hung <[email protected]>
>>>> CC: Harry Wentland <[email protected]>
>>>> ---
>>>>   .../tests/amdgpu_dm_connector_test.c          | 37 
>>>> ++++++++++---------
>>>>   .../amdgpu_dm/tests/amdgpu_dm_kunit_helpers.c |  3 +-
>>>>   .../amdgpu_dm/tests/amdgpu_dm_wb_test.c       |  5 ++-
>>>>   3 files changed, 24 insertions(+), 21 deletions(-)
>>>>
>>>> diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/tests/ 
>>>> amdgpu_dm_connector_test.c b/drivers/gpu/drm/amd/display/amdgpu_dm/ 
>>>> tests/amdgpu_dm_connector_test.c
>>>> index 0a5d439f66c3..93a854d4fdfa 100644
>>>> --- a/drivers/gpu/drm/amd/display/amdgpu_dm/tests/ 
>>>> amdgpu_dm_connector_test.c
>>>> +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/tests/ 
>>>> amdgpu_dm_connector_test.c
>>>> @@ -12,6 +12,7 @@
>>>>   #include <drm/drm_crtc.h>
>>>>   #include <drm/drm_edid.h>
>>>>   #include <drm/drm_kunit_helpers.h>
>>>> +#include <drm/drm_managed.h>
>>>>   #include <drm/drm_mode_object.h>
>>>>   #include <drm/drm_property.h>
>>>>   #include <linux/hdmi.h>
>>>> @@ -1449,7 +1450,7 @@ static void 
>>>> dm_test_funcs_reset_sets_defaults(struct kunit *test)
>>>>                              DRIVER_MODESET);
>>>>       KUNIT_ASSERT_NOT_ERR_OR_NULL(test, drm);
>>>>   -    connector = kunit_kzalloc(test, sizeof(*connector), 
>>>> GFP_KERNEL);
>>>> +    connector = drmm_kzalloc(drm, sizeof(*connector), GFP_KERNEL);
>>>>       KUNIT_ASSERT_NOT_NULL(test, connector);
>>>>         drmm_connector_init(drm, connector, &dm_test_connector_funcs,
>>>> @@ -1488,7 +1489,7 @@ static void 
>>>> dm_test_funcs_reset_edp_abm_level(struct kunit *test)
>>>>                              DRIVER_MODESET);
>>>>       KUNIT_ASSERT_NOT_ERR_OR_NULL(test, drm);
>>>>   -    connector = kunit_kzalloc(test, sizeof(*connector), 
>>>> GFP_KERNEL);
>>>> +    connector = drmm_kzalloc(drm, sizeof(*connector), GFP_KERNEL);
>>>>       KUNIT_ASSERT_NOT_NULL(test, connector);
>>>>         drmm_connector_init(drm, connector, &dm_test_connector_funcs,
>>>> @@ -1526,7 +1527,7 @@ static void 
>>>> dm_test_funcs_reset_edp_abm_disabled(struct kunit *test)
>>>>                              DRIVER_MODESET);
>>>>       KUNIT_ASSERT_NOT_ERR_OR_NULL(test, drm);
>>>>   -    connector = kunit_kzalloc(test, sizeof(*connector), 
>>>> GFP_KERNEL);
>>>> +    connector = drmm_kzalloc(drm, sizeof(*connector), GFP_KERNEL);
>>>>       KUNIT_ASSERT_NOT_NULL(test, connector);
>>>>         drmm_connector_init(drm, connector, &dm_test_connector_funcs,
>>>> @@ -1568,7 +1569,7 @@ static void 
>>>> dm_test_atomic_dup_state_copies_fields(struct kunit *test)
>>>>                              DRIVER_MODESET);
>>>>       KUNIT_ASSERT_NOT_ERR_OR_NULL(test, drm);
>>>>   -    connector = kunit_kzalloc(test, sizeof(*connector), 
>>>> GFP_KERNEL);
>>>> +    connector = drmm_kzalloc(drm, sizeof(*connector), GFP_KERNEL);
>>>>       KUNIT_ASSERT_NOT_NULL(test, connector);
>>>>         drmm_connector_init(drm, connector, &dm_test_connector_funcs,
>>>> @@ -2359,8 +2360,8 @@ static void setup_panel_type_fixture(struct 
>>>> kunit *test,
>>>>       KUNIT_ASSERT_NOT_ERR_OR_NULL(test, fixture->drm);
>>>>       fixture->adev = drm_to_adev(fixture->drm);
>>>>   -    fixture->aconnector = kunit_kzalloc(test, sizeof(*fixture- 
>>>> >aconnector),
>>>> -                        GFP_KERNEL);
>>>> +    fixture->aconnector = drmm_kzalloc(fixture->drm, 
>>>> sizeof(*fixture->aconnector),
>>>> +                       GFP_KERNEL);
>>>>       KUNIT_ASSERT_NOT_ERR_OR_NULL(test, fixture->aconnector);
>>>>       fixture->link = kunit_kzalloc(test, sizeof(*fixture->link), 
>>>> GFP_KERNEL);
>>>>       KUNIT_ASSERT_NOT_ERR_OR_NULL(test, fixture->link);
>>>> @@ -2554,9 +2555,9 @@ static void 
>>>> dm_test_update_subconnector_dp_with_sink(struct kunit *test)
>>>>                              DRIVER_MODESET);
>>>>       KUNIT_ASSERT_NOT_ERR_OR_NULL(test, drm);
>>>>   -    aconnector = kunit_kzalloc(test, sizeof(*aconnector), 
>>>> GFP_KERNEL);
>>>> +    aconnector = drmm_kzalloc(drm, sizeof(*aconnector), GFP_KERNEL);
>>>>       KUNIT_ASSERT_NOT_NULL(test, aconnector);
>>>> -    link = kunit_kzalloc(test, sizeof(*link), GFP_KERNEL);
>>>> +    link = drmm_kzalloc(drm, sizeof(*link), GFP_KERNEL);
>>>>       KUNIT_ASSERT_NOT_NULL(test, link);
>>>>         drmm_connector_init(drm, &aconnector->base, 
>>>> &dm_test_connector_funcs,
>>>> @@ -2598,9 +2599,9 @@ static void 
>>>> dm_test_update_subconnector_dp_no_sink(struct kunit *test)
>>>>                              DRIVER_MODESET);
>>>>       KUNIT_ASSERT_NOT_ERR_OR_NULL(test, drm);
>>>>   -    aconnector = kunit_kzalloc(test, sizeof(*aconnector), 
>>>> GFP_KERNEL);
>>>> +    aconnector = drmm_kzalloc(drm, sizeof(*aconnector), GFP_KERNEL);
>>>>       KUNIT_ASSERT_NOT_NULL(test, aconnector);
>>>> -    link = kunit_kzalloc(test, sizeof(*link), GFP_KERNEL);
>>>> +    link = drmm_kzalloc(drm, sizeof(*link), GFP_KERNEL);
>>>>       KUNIT_ASSERT_NOT_NULL(test, link);
>>>>         drmm_connector_init(drm, &aconnector->base, 
>>>> &dm_test_connector_funcs,
>>>> @@ -2641,9 +2642,9 @@ static void 
>>>> dm_test_update_subconnector_non_dp_noop(struct kunit *test)
>>>>                              DRIVER_MODESET);
>>>>       KUNIT_ASSERT_NOT_ERR_OR_NULL(test, drm);
>>>>   -    aconnector = kunit_kzalloc(test, sizeof(*aconnector), 
>>>> GFP_KERNEL);
>>>> +    aconnector = drmm_kzalloc(drm, sizeof(*aconnector), GFP_KERNEL);
>>>>       KUNIT_ASSERT_NOT_NULL(test, aconnector);
>>>> -    link = kunit_kzalloc(test, sizeof(*link), GFP_KERNEL);
>>>> +    link = drmm_kzalloc(drm, sizeof(*link), GFP_KERNEL);
>>>>       KUNIT_ASSERT_NOT_NULL(test, link);
>>>>         drmm_connector_init(drm, &aconnector->base, 
>>>> &dm_test_connector_funcs,
>>>> @@ -2657,7 +2658,7 @@ static void 
>>>> dm_test_update_subconnector_non_dp_noop(struct kunit *test)
>>>>         link->dpcd_caps.dongle_type = 
>>>> DISPLAY_DONGLE_DP_HDMI_CONVERTER;
>>>>       aconnector->dc_link = link;
>>>> -    aconnector->dc_sink = kunit_kzalloc(test, sizeof(*aconnector- 
>>>> >dc_sink), GFP_KERNEL);
>>>> +    aconnector->dc_sink = drmm_kzalloc(drm, sizeof(*aconnector- 
>>>> >dc_sink), GFP_KERNEL);
>>>>       KUNIT_ASSERT_NOT_NULL(test, aconnector->dc_sink);
>>>>         update_subconnector_property(aconnector);
>>>> @@ -2804,7 +2805,7 @@ static struct amdgpu_dm_connector 
>>>> *dm_test_add_connector(struct kunit *test,
>>>>   {
>>>>       struct amdgpu_dm_connector *aconnector;
>>>>   -    aconnector = kunit_kzalloc(test, sizeof(*aconnector), 
>>>> GFP_KERNEL);
>>>> +    aconnector = drmm_kzalloc(drm, sizeof(*aconnector), GFP_KERNEL);
>>>>       KUNIT_ASSERT_NOT_NULL(test, aconnector);
>>>>         KUNIT_ASSERT_EQ(test,
>>>> @@ -3103,7 +3104,7 @@ static struct dm_test_panel_ctx 
>>>> *dm_test_panel_ctx_alloc(struct kunit *test)
>>>>       KUNIT_ASSERT_NOT_NULL(test, prop);
>>>>       ctx->drm->mode_config.panel_type_property = prop;
>>>>   -    ctx->aconnector = kunit_kzalloc(test, sizeof(*ctx- 
>>>> >aconnector), GFP_KERNEL);
>>>> +    ctx->aconnector = drmm_kzalloc(ctx->drm, sizeof(*ctx- 
>>>> >aconnector), GFP_KERNEL);
>>>>       KUNIT_ASSERT_NOT_NULL(test, ctx->aconnector);
>>>>       KUNIT_ASSERT_EQ(test,
>>>>           drmm_connector_init(ctx->drm, &ctx->aconnector->base,
>>>> @@ -3112,7 +3113,7 @@ static struct dm_test_panel_ctx 
>>>> *dm_test_panel_ctx_alloc(struct kunit *test)
>>>> drm_object_attach_property(&ctx->aconnector->base.base, prop,
>>>>                      DRM_MODE_PANEL_TYPE_UNKNOWN);
>>>>   -    ctx->link = kunit_kzalloc(test, sizeof(*ctx->link), 
>>>> GFP_KERNEL);
>>>> +    ctx->link = drmm_kzalloc(ctx->drm, sizeof(*ctx->link), 
>>>> GFP_KERNEL);
>>>>       KUNIT_ASSERT_NOT_NULL(test, ctx->link);
>>>>       ctx->aconnector->dc_link = ctx->link;
>>>>   @@ -3376,14 +3377,14 @@ static struct dm_test_fill_ctx 
>>>> *dm_test_fill_ctx_alloc(struct kunit *test)
>>>>                                  DRIVER_MODESET);
>>>>       KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ctx->drm);
>>>>   -    ctx->aconnector = kunit_kzalloc(test, sizeof(*ctx- 
>>>> >aconnector), GFP_KERNEL);
>>>> +    ctx->aconnector = drmm_kzalloc(ctx->drm, sizeof(*ctx- 
>>>> >aconnector), GFP_KERNEL);
>>>>       KUNIT_ASSERT_NOT_NULL(test, ctx->aconnector);
>>>>       KUNIT_ASSERT_EQ(test,
>>>>           drmm_connector_init(ctx->drm, &ctx->aconnector->base,
>>>>                       &dm_test_connector_funcs,
>>>>                       DRM_MODE_CONNECTOR_DisplayPort, NULL), 0);
>>>>   -    ctx->conn_state = kunit_kzalloc(test, sizeof(*ctx- 
>>>> >conn_state), GFP_KERNEL);
>>>> +    ctx->conn_state = drmm_kzalloc(ctx->drm, sizeof(*ctx- 
>>>> >conn_state), GFP_KERNEL);
>>>>       KUNIT_ASSERT_NOT_NULL(test, ctx->conn_state);
>>>>       ctx->stream = kunit_kzalloc(test, sizeof(*ctx->stream), 
>>>> GFP_KERNEL);
>>>>       KUNIT_ASSERT_NOT_NULL(test, ctx->stream);
>>>> diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/tests/ 
>>>> amdgpu_dm_kunit_helpers.c b/drivers/gpu/drm/amd/display/amdgpu_dm/ 
>>>> tests/amdgpu_dm_kunit_helpers.c
>>>> index 58615cdbe854..7d5e3823b33b 100644
>>>> --- a/drivers/gpu/drm/amd/display/amdgpu_dm/tests/ 
>>>> amdgpu_dm_kunit_helpers.c
>>>> +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/tests/ 
>>>> amdgpu_dm_kunit_helpers.c
>>>> @@ -8,6 +8,7 @@
>>>>   #include <kunit/test.h>
>>>>   #include <linux/module.h>
>>>>   #include <drm/drm_kunit_helpers.h>
>>>> +#include <drm/drm_managed.h>
>>>>     #include "dc.h"
>>>>   #include "core_types.h"
>>>> @@ -127,7 +128,7 @@ struct amdgpu_dm_connector 
>>>> *dm_kunit_alloc_connector(struct kunit *test,
>>>>   {
>>>>       struct amdgpu_dm_connector *aconnector;
>>>>   -    aconnector = kunit_kzalloc(test, sizeof(*aconnector), 
>>>> GFP_KERNEL);
>>>> +    aconnector = drmm_kzalloc(adev_to_drm(adev), 
>>>> sizeof(*aconnector), GFP_KERNEL);
>>>>       KUNIT_ASSERT_NOT_NULL(test, aconnector);
>>>>         if (adev)
>>>> diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/tests/ 
>>>> amdgpu_dm_wb_test.c b/drivers/gpu/drm/amd/display/amdgpu_dm/tests/ 
>>>> amdgpu_dm_wb_test.c
>>>> index b43bc244487e..3454cf371414 100644
>>>> --- a/drivers/gpu/drm/amd/display/amdgpu_dm/tests/amdgpu_dm_wb_test.c
>>>> +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/tests/amdgpu_dm_wb_test.c
>>>> @@ -12,6 +12,7 @@
>>>>   #include <drm/drm_fourcc.h>
>>>>   #include <drm/drm_framebuffer.h>
>>>>   #include <drm/drm_kunit_helpers.h>
>>>> +#include <drm/drm_managed.h>
>>>>   #include <drm/drm_mode.h>
>>>>   #include <drm/drm_modes.h>
>>>>   #include <drm/drm_writeback.h>
>>>> @@ -266,7 +267,7 @@ static void 
>>>> dm_test_wb_get_modes_returns_modes(struct kunit *test)
>>>>                              DRIVER_MODESET | DRIVER_ATOMIC);
>>>>       KUNIT_ASSERT_NOT_ERR_OR_NULL(test, drm);
>>>>   -    connector = kunit_kzalloc(test, sizeof(*connector), 
>>>> GFP_KERNEL);
>>>> +    connector = drmm_kzalloc(drm, sizeof(*connector), GFP_KERNEL);
>>>>       KUNIT_ASSERT_NOT_NULL(test, connector);
>>>>         drmm_connector_init(drm, connector, 
>>>> &dm_wb_test_connector_funcs,
>>>> @@ -301,7 +302,7 @@ static void 
>>>> dm_test_wb_get_modes_bounded_by_max(struct kunit *test)
>>>>                              DRIVER_MODESET | DRIVER_ATOMIC);
>>>>       KUNIT_ASSERT_NOT_ERR_OR_NULL(test, drm);
>>>>   -    connector = kunit_kzalloc(test, sizeof(*connector), 
>>>> GFP_KERNEL);
>>>> +    connector = drmm_kzalloc(drm, sizeof(*connector), GFP_KERNEL);
>>>>       KUNIT_ASSERT_NOT_NULL(test, connector);
>>>>         drmm_connector_init(drm, connector, 
>>>> &dm_wb_test_connector_funcs,
>>>
>>
>