modprobe drm_hdmi_state_helper_test and then rmmod it, the following
memory leak occurs.

The `mode` allocated in drm_mode_duplicate() called by
drm_display_mode_from_cea_vic() is not freed, which cause the memory leak:

	unreferenced object 0xffffff80ccd18100 (size 128):
	  comm "kunit_try_catch", pid 1851, jiffies 4295059695
	  hex dump (first 32 bytes):
	    57 62 00 00 80 02 90 02 f0 02 20 03 00 00 e0 01  Wb........ .....
	    ea 01 ec 01 0d 02 00 00 0a 00 00 00 00 00 00 00  ................
	  backtrace (crc c2f1aa95):
	    [<000000000f10b11b>] kmemleak_alloc+0x34/0x40
	    [<000000001cd4cf73>] __kmalloc_cache_noprof+0x26c/0x2f4
	    [<00000000f1f3cffa>] drm_mode_duplicate+0x44/0x19c
	    [<000000008cbeef13>] drm_display_mode_from_cea_vic+0x88/0x98
	    [<0000000019daaacf>] 0xffffffedc11ae69c
	    [<000000000aad0f85>] kunit_try_run_case+0x13c/0x3ac
	    [<00000000a9210bac>] kunit_generic_run_threadfn_adapter+0x80/0xec
	    [<000000000a0b2e9e>] kthread+0x2e8/0x374
	    [<00000000bd668858>] ret_from_fork+0x10/0x20
	......

Free `mode` by using drm_kunit_helper_display_mode_from_cea_vic()
to fix it.

Cc: stable@vger.kernel.org
Fixes: 4af70f19e559 ("drm/tests: Add RGB Quantization tests")
Signed-off-by: Jinjie Ruan <ruanjinjie@huawei.com>
---
v2:
- Fix it with new introduced helper instead of drm_mode_destroy().
- Update the commit message.
---
 drivers/gpu/drm/tests/drm_hdmi_state_helper_test.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/tests/drm_hdmi_state_helper_test.c b/drivers/gpu/drm/tests/drm_hdmi_state_helper_test.c
index 34ee95d41f29..bb9af542cb43 100644
--- a/drivers/gpu/drm/tests/drm_hdmi_state_helper_test.c
+++ b/drivers/gpu/drm/tests/drm_hdmi_state_helper_test.c
@@ -441,7 +441,7 @@ static void drm_test_check_broadcast_rgb_auto_cea_mode_vic_1(struct kunit *test)
 	ctx = drm_kunit_helper_acquire_ctx_alloc(test);
 	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ctx);
 
-	mode = drm_display_mode_from_cea_vic(drm, 1);
+	mode = drm_kunit_helper_display_mode_from_cea_vic(test, drm, 1);
 	KUNIT_ASSERT_NOT_NULL(test, mode);
 
 	drm = &priv->drm;
@@ -555,7 +555,7 @@ static void drm_test_check_broadcast_rgb_full_cea_mode_vic_1(struct kunit *test)
 	ctx = drm_kunit_helper_acquire_ctx_alloc(test);
 	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ctx);
 
-	mode = drm_display_mode_from_cea_vic(drm, 1);
+	mode = drm_kunit_helper_display_mode_from_cea_vic(test, drm, 1);
 	KUNIT_ASSERT_NOT_NULL(test, mode);
 
 	drm = &priv->drm;
@@ -671,7 +671,7 @@ static void drm_test_check_broadcast_rgb_limited_cea_mode_vic_1(struct kunit *te
 	ctx = drm_kunit_helper_acquire_ctx_alloc(test);
 	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ctx);
 
-	mode = drm_display_mode_from_cea_vic(drm, 1);
+	mode = drm_kunit_helper_display_mode_from_cea_vic(test, drm, 1);
 	KUNIT_ASSERT_NOT_NULL(test, mode);
 
 	drm = &priv->drm;
@@ -1263,7 +1263,7 @@ static void drm_test_check_output_bpc_format_vic_1(struct kunit *test)
 	ctx = drm_kunit_helper_acquire_ctx_alloc(test);
 	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ctx);
 
-	mode = drm_display_mode_from_cea_vic(drm, 1);
+	mode = drm_kunit_helper_display_mode_from_cea_vic(test, drm, 1);
 	KUNIT_ASSERT_NOT_NULL(test, mode);
 
 	/*
-- 
2.34.1

On Mon, Oct 14, 2024 at 08:52:04PM GMT, Jinjie Ruan wrote:
> modprobe drm_hdmi_state_helper_test and then rmmod it, the following
> memory leak occurs.
> 
> The `mode` allocated in drm_mode_duplicate() called by
> drm_display_mode_from_cea_vic() is not freed, which cause the memory leak:
> 
> 	unreferenced object 0xffffff80ccd18100 (size 128):
> 	  comm "kunit_try_catch", pid 1851, jiffies 4295059695
> 	  hex dump (first 32 bytes):
> 	    57 62 00 00 80 02 90 02 f0 02 20 03 00 00 e0 01  Wb........ .....
> 	    ea 01 ec 01 0d 02 00 00 0a 00 00 00 00 00 00 00  ................
> 	  backtrace (crc c2f1aa95):
> 	    [<000000000f10b11b>] kmemleak_alloc+0x34/0x40
> 	    [<000000001cd4cf73>] __kmalloc_cache_noprof+0x26c/0x2f4
> 	    [<00000000f1f3cffa>] drm_mode_duplicate+0x44/0x19c
> 	    [<000000008cbeef13>] drm_display_mode_from_cea_vic+0x88/0x98
> 	    [<0000000019daaacf>] 0xffffffedc11ae69c
> 	    [<000000000aad0f85>] kunit_try_run_case+0x13c/0x3ac
> 	    [<00000000a9210bac>] kunit_generic_run_threadfn_adapter+0x80/0xec
> 	    [<000000000a0b2e9e>] kthread+0x2e8/0x374
> 	    [<00000000bd668858>] ret_from_fork+0x10/0x20
> 	......
> 
> Free `mode` by using drm_kunit_helper_display_mode_from_cea_vic()
> to fix it.
> 
> Cc: stable@vger.kernel.org
> Fixes: 4af70f19e559 ("drm/tests: Add RGB Quantization tests")
> Signed-off-by: Jinjie Ruan <ruanjinjie@huawei.com>

Acked-by: Maxime Ripard <mripard@kernel.org>

Maxime