Re: [PATCH] drm/mst: Fix NULL pointer dereference at drm_dp_add_payload_part2

Mario Limonciello <mario.limonciello@xxxxxxx> · Thu, 9 May 2024 14:18:02 -0500

On 5/9/2024 07:43, Linux regression tracking (Thorsten Leemhuis) wrote:
On 18.04.24 21:43, Harry Wentland wrote:
On 2024-03-07 01:29, Wayne Lin wrote:
[Why]
Commit:
- commit 5aa1dfcdf0a4 ("drm/mst: Refactor the flow for payload allocation/removement")
accidently overwrite the commit
- commit 54d217406afe ("drm: use mgr->dev in drm_dbg_kms in drm_dp_add_payload_part2")
which cause regression.

[How]
Recover the original NULL fix and remove the unnecessary input parameter 'state' for
drm_dp_add_payload_part2().

Fixes: 5aa1dfcdf0a4 ("drm/mst: Refactor the flow for payload allocation/removement")
Reported-by: Leon Weiß <leon.weiss@xxxxxxxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/38c253ea42072cc825dc969ac4e6b9b600371cc8.camel@xxxxxxxxxxxxxxxxxx/
Cc: lyude@xxxxxxxxxx
Cc: imre.deak@xxxxxxxxx
Cc: stable@xxxxxxxxxxxxxxx
Cc: regressions@xxxxxxxxxxxxxxx
Signed-off-by: Wayne Lin <Wayne.Lin@xxxxxxx>

I haven't been deep in MST code in a while but this all looks
pretty straightforward and good.

Reviewed-by: Harry Wentland <harry.wentland@xxxxxxx>

Hmmm, that was three weeks ago, but it seems since then nothing happened
to fix the linked regression through this or some other patch. Is there
a reason? The build failure report from the CI maybe?

It touches files outside of amd but only has an ack from AMD.  I think 
we /probably/ want an ack from i915 and nouveau to take it through.


Wayne Lin, do you know what's up?

Ciao, Thorsten

---
  drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_helpers.c | 2 +-
  drivers/gpu/drm/display/drm_dp_mst_topology.c             | 4 +---
  drivers/gpu/drm/i915/display/intel_dp_mst.c               | 2 +-
  drivers/gpu/drm/nouveau/dispnv50/disp.c                   | 2 +-
  include/drm/display/drm_dp_mst_helper.h                   | 1 -
  5 files changed, 4 insertions(+), 7 deletions(-)

diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_helpers.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_helpers.c
index c27063305a13..2c36f3d00ca2 100644
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_helpers.c
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_helpers.c
@@ -363,7 +363,7 @@ void dm_helpers_dp_mst_send_payload_allocation(
  	mst_state = to_drm_dp_mst_topology_state(mst_mgr->base.state);
  	new_payload = drm_atomic_get_mst_payload_state(mst_state, aconnector->mst_output_port);
  
-	ret = drm_dp_add_payload_part2(mst_mgr, mst_state->base.state, new_payload);
+	ret = drm_dp_add_payload_part2(mst_mgr, new_payload);
  
  	if (ret) {
  		amdgpu_dm_set_mst_status(&aconnector->mst_status,
diff --git a/drivers/gpu/drm/display/drm_dp_mst_topology.c b/drivers/gpu/drm/display/drm_dp_mst_topology.c
index 03d528209426..95fd18f24e94 100644
--- a/drivers/gpu/drm/display/drm_dp_mst_topology.c
+++ b/drivers/gpu/drm/display/drm_dp_mst_topology.c
@@ -3421,7 +3421,6 @@ EXPORT_SYMBOL(drm_dp_remove_payload_part2);
  /**
   * drm_dp_add_payload_part2() - Execute payload update part 2
   * @mgr: Manager to use.
- * @state: The global atomic state
   * @payload: The payload to update
   *
   * If @payload was successfully assigned a starting time slot by drm_dp_add_payload_part1(), this
@@ -3430,14 +3429,13 @@ EXPORT_SYMBOL(drm_dp_remove_payload_part2);
   * Returns: 0 on success, negative error code on failure.
   */
  int drm_dp_add_payload_part2(struct drm_dp_mst_topology_mgr *mgr,
-			     struct drm_atomic_state *state,
  			     struct drm_dp_mst_atomic_payload *payload)
  {
  	int ret = 0;
  
  	/* Skip failed payloads */
  	if (payload->payload_allocation_status != DRM_DP_MST_PAYLOAD_ALLOCATION_DFP) {
-		drm_dbg_kms(state->dev, "Part 1 of payload creation for %s failed, skipping part 2\n",
+		drm_dbg_kms(mgr->dev, "Part 1 of payload creation for %s failed, skipping part 2\n",
  			    payload->port->connector->name);
  		return -EIO;
  	}
diff --git a/drivers/gpu/drm/i915/display/intel_dp_mst.c b/drivers/gpu/drm/i915/display/intel_dp_mst.c
index 53aec023ce92..2fba66aec038 100644
--- a/drivers/gpu/drm/i915/display/intel_dp_mst.c
+++ b/drivers/gpu/drm/i915/display/intel_dp_mst.c
@@ -1160,7 +1160,7 @@ static void intel_mst_enable_dp(struct intel_atomic_state *state,
  	if (first_mst_stream)
  		intel_ddi_wait_for_fec_status(encoder, pipe_config, true);
  
-	drm_dp_add_payload_part2(&intel_dp->mst_mgr, &state->base,
+	drm_dp_add_payload_part2(&intel_dp->mst_mgr,
  				 drm_atomic_get_mst_payload_state(mst_state, connector->port));
  
  	if (DISPLAY_VER(dev_priv) >= 12)
diff --git a/drivers/gpu/drm/nouveau/dispnv50/disp.c b/drivers/gpu/drm/nouveau/dispnv50/disp.c
index 0c3d88ad0b0e..88728a0b2c25 100644
--- a/drivers/gpu/drm/nouveau/dispnv50/disp.c
+++ b/drivers/gpu/drm/nouveau/dispnv50/disp.c
@@ -915,7 +915,7 @@ nv50_msto_cleanup(struct drm_atomic_state *state,
  		msto->disabled = false;
  		drm_dp_remove_payload_part2(mgr, new_mst_state, old_payload, new_payload);
  	} else if (msto->enabled) {
-		drm_dp_add_payload_part2(mgr, state, new_payload);
+		drm_dp_add_payload_part2(mgr, new_payload);
  		msto->enabled = false;
  	}
  }
diff --git a/include/drm/display/drm_dp_mst_helper.h b/include/drm/display/drm_dp_mst_helper.h
index 9b19d8bd520a..6c9145abc7e2 100644
--- a/include/drm/display/drm_dp_mst_helper.h
+++ b/include/drm/display/drm_dp_mst_helper.h
@@ -851,7 +851,6 @@ int drm_dp_add_payload_part1(struct drm_dp_mst_topology_mgr *mgr,
  			     struct drm_dp_mst_topology_state *mst_state,
  			     struct drm_dp_mst_atomic_payload *payload);
  int drm_dp_add_payload_part2(struct drm_dp_mst_topology_mgr *mgr,
-			     struct drm_atomic_state *state,
  			     struct drm_dp_mst_atomic_payload *payload);
  void drm_dp_remove_payload_part1(struct drm_dp_mst_topology_mgr *mgr,
  				 struct drm_dp_mst_topology_state *mst_state,











