drm/amd/display: Fix potential null dereference

[ Upstream commit 52f1783ff4146344342422c1cd94fcb4ce39b6fe ]

The adev->dm.dc pointer can be NULL and dereferenced in amdgpu_dm_fini()
without checking.

Add a NULL pointer check before calling dc_dmub_srv_destroy().

Found by Linux Verification Center (linuxtesting.org) with SVACE.

Fixes: 9a71c7d31734 ("drm/amd/display: Register DMUB service with DC")
Signed-off-by: Igor Artemiev <Igor.A.Artemiev@mcst.ru>
Signed-off-by: Hamza Mahfooz <hamza.mahfooz@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
index 6c5ea99223bab5e671698e3f20ea984445083786..99b99f0b42c064c81aa913afae53460e962f7d9a 100644 (file)
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
@@ -1763,7 +1763,8 @@ static void amdgpu_dm_fini(struct amdgpu_device *adev)
                dc_deinit_callbacks(adev->dm.dc);
 #endif
 
-       dc_dmub_srv_destroy(&adev->dm.dc->ctx->dmub_srv);
+       if (adev->dm.dc)
+               dc_dmub_srv_destroy(&adev->dm.dc->ctx->dmub_srv);
 
        if (dc_enable_dmub_notifications(adev->dm.dc)) {
                kfree(adev->dm.dmub_notify);