[PATCH 6.7 451/713] drm/amd/display: fix NULL checks for adev->dm.dc in amdgpu_dm_fini()

Sasha Levin
2024-03-24T22:54:47Z

From: Nikita Zhandarovich <n.zhandarovich@fintech.ru>

[ Upstream commit 2a3cfb9a24a28da9cc13d2c525a76548865e182c ]

Since 'adev->dm.dc' in amdgpu_dm_fini() might turn out to be NULL
before the call to dc_enable_dmub_notifications(), check
beforehand to ensure there will not be a possible NULL-ptr-deref
there.

Also, since commit 1e88eb1b2c25 ("drm/amd/display: Drop
CONFIG_DRM_AMD_DC_HDCP") there are two separate checks for NULL in
'adev->dm.dc' before dc_deinit_callbacks() and dc_dmub_srv_destroy().
Clean up by combining them all under one 'if'.

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

Fixes: 81927e2808be ("drm/amd/display: Support for DMUB AUX")
Signed-off-by: Nikita Zhandarovich <n.zhandarovich@fintech.ru>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
.../gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 16 +++++++---------
1 file changed, 7 insertions(+), 9 deletions(-)

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 272c27495ede6..49f0c9454a6e6 100644
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
@@ -1896,17 +1896,15 @@ static void amdgpu_dm_fini(struct amdgpu_device *adev)
adev->dm.hdcp_workqueue = NULL;
}

- if (adev->dm.dc)
+ if (adev->dm.dc) {
dc_deinit_callbacks(adev->dm.dc);
-
- 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);
- adev->dm.dmub_notify = NULL;
- destroy_workqueue(adev->dm.delayed_hpd_wq);
- adev->dm.delayed_hpd_wq = NULL;
+ if (dc_enable_dmub_notifications(adev->dm.dc)) {
+ kfree(adev->dm.dmub_notify);
+ adev->dm.dmub_notify = NULL;
+ destroy_workqueue(adev->dm.delayed_hpd_wq);
+ adev->dm.delayed_hpd_wq = NULL;
+ }
}

if (adev->dm.dmub_bo)
--
2.43.0