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

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.

> 
> 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,
>>
>