Re: [PATCH] drm/amd/display: Fix potential NULL pointer dereferences in amdgpu_dm_atomic_commit_tail

From: Andrey Grodzovsky
Date: Tue Nov 28 2017 - 09:33:37 EST


Reviewed-by: Andrey Grodzovsky <andrey.grodzovsky@xxxxxxx>

Thanks,

Andrey

On 11/27/2017 09:57 AM, Gustavo A. R. Silva wrote:
dm_new_crtc_state->stream and disconnected_acrtc are being dereferenced
before they are null checked, hence there is a potential null pointer
dereference.

Fix this by null checking such pointers before they are dereferenced.

Addresses-Coverity-ID: 1423745 ("Dereference before null check")
Addresses-Coverity-ID: 1423833 ("Dereference before null check")
Fixes: e7b07ceef2a6 ("drm/amd/display: Merge amdgpu_dm_types and amdgpu_dm")
Fixes: 54d765752467 ("drm/amd/display: Unify amdgpu_dm state variable namings.")
Signed-off-by: Gustavo A. R. Silva <garsilva@xxxxxxxxxxxxxx>
---
drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 12 +++++++-----
1 file changed, 7 insertions(+), 5 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 889ed24..3bdd137 100644
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
@@ -4190,6 +4190,9 @@ static void amdgpu_dm_atomic_commit_tail(struct drm_atomic_state *state)
dm_new_crtc_state = to_dm_crtc_state(new_crtc_state);
+ if (!dm_new_crtc_state->stream)
+ continue;
+
update_stream_scaling_settings(&dm_new_con_state->base.crtc->mode,
dm_new_con_state, (struct dc_stream_state *)dm_new_crtc_state->stream);
@@ -4197,9 +4200,6 @@ static void amdgpu_dm_atomic_commit_tail(struct drm_atomic_state *state)
WARN_ON(!status);
WARN_ON(!status->plane_count);
- if (!dm_new_crtc_state->stream)
- continue;
-
/*TODO How it works with MPO ?*/
if (!dc_commit_planes_to_stream(
dm->dc,
@@ -4332,9 +4332,11 @@ void dm_restore_drm_connector_state(struct drm_device *dev,
return;
disconnected_acrtc = to_amdgpu_crtc(connector->encoder->crtc);
- acrtc_state = to_dm_crtc_state(disconnected_acrtc->base.state);
+ if (!disconnected_acrtc)
+ return;
- if (!disconnected_acrtc || !acrtc_state->stream)
+ acrtc_state = to_dm_crtc_state(disconnected_acrtc->base.state);
+ if (!acrtc_state->stream)
return;
/*