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

[Lin, Wayne]

[Public]

Ping for code review. Thanks!

Regards,
Wayne

________________________________________
From: Wayne Lin <Wayne.Lin at amd.com>
Sent: Thursday, March 7, 2024 14:29
To: dri-devel at lists.freedesktop.org; amd-gfx at lists.freedesktop.org; intel-gfx at lists.freedesktop.org
Cc: lyude at redhat.com; Wentland, Harry; imre.deak at intel.com; Lin, Wayne; Leon Weiß; stable at vger.kernel.org; regressions at lists.linux.dev
Subject: [PATCH] drm/mst: Fix NULL pointer dereference at drm_dp_add_payload_part2

[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 at ruhr-uni-bochum.de>
Link: https://lore.kernel.org/r/38c253ea42072cc825dc969ac4e6b9b600371cc8.camel@ruhr-uni-bochum.de/
Cc: lyude at redhat.com
Cc: imre.deak at intel.com
Cc: stable at vger.kernel.org
Cc: regressions at lists.linux.dev
Signed-off-by: Wayne Lin <Wayne.Lin at amd.com>
---
 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,
--
2.37.3