drm/amd/display: Fix invalid DPIA AUX reply causing system hang

[Why]
Some DPIA AUX replies have incorrect data length from original request.
This could lead to overwriting of destination buffer if reply length is
larger, which could cause invalid access to stack since many destination
buffers are declared as local variables.

[How]
Check for invalid length from DPIA AUX replies and trigger a retry if
reply length is not the same as original request. A DRM_WARN() dmesg log
is also produced.

Reviewed-by: Roman Li <[e-mail]>
Acked-by: Tom Chung <[e-mail]>
Signed-off-by: Stylon Wang <[e-mail]>
Tested-by: Daniel Wheeler <[e-mail]>
Signed-off-by: Alex Deucher <[e-mail]>
Cc: [e-mail] # 6.0.x

drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c

···
 /* Number of bytes in PSP footer for firmware. */
 #define PSP_FOOTER_BYTES 0x100
 
+/*
+ * DMUB Async to Sync Mechanism Status
+ */
+#define DMUB_ASYNC_TO_SYNC_ACCESS_FAIL 1
+#define DMUB_ASYNC_TO_SYNC_ACCESS_TIMEOUT 2
+#define DMUB_ASYNC_TO_SYNC_ACCESS_SUCCESS 3
+#define DMUB_ASYNC_TO_SYNC_ACCESS_INVALID 4
+
 /**
  * DOC: overview
  *
···
 			*operation_result = AUX_RET_ERROR_TIMEOUT;
 		} else if (status_type == DMUB_ASYNC_TO_SYNC_ACCESS_FAIL) {
 			*operation_result = AUX_RET_ERROR_ENGINE_ACQUIRE;
+		} else if (status_type == DMUB_ASYNC_TO_SYNC_ACCESS_INVALID) {
+			*operation_result = AUX_RET_ERROR_INVALID_REPLY;
 		} else {
 			*operation_result = AUX_RET_ERROR_UNKNOWN;
 		}
···
 			payload->reply[0] = adev->dm.dmub_notify->aux_reply.command;
 			if (!payload->write && adev->dm.dmub_notify->aux_reply.length &&
 			    payload->reply[0] == AUX_TRANSACTION_REPLY_AUX_ACK) {
+
+				if (payload->length != adev->dm.dmub_notify->aux_reply.length) {
+					DRM_WARN("invalid read from DPIA AUX %x(%d) got length %d!\n",
+							payload->address, payload->length,
+							adev->dm.dmub_notify->aux_reply.length);
+					return amdgpu_dm_set_dmub_async_sync_status(is_cmd_aux, ctx,
+							DMUB_ASYNC_TO_SYNC_ACCESS_INVALID,
+							(uint32_t *)operation_result);
+				}
+
 				memcpy(payload->data, adev->dm.dmub_notify->aux_reply.data,
 				       adev->dm.dmub_notify->aux_reply.length);
 			}

drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.h

···
 #define AMDGPU_DMUB_NOTIFICATION_MAX 5
 
 /*
- * DMUB Async to Sync Mechanism Status
- */
-#define DMUB_ASYNC_TO_SYNC_ACCESS_FAIL 1
-#define DMUB_ASYNC_TO_SYNC_ACCESS_TIMEOUT 2
-#define DMUB_ASYNC_TO_SYNC_ACCESS_SUCCESS 3
-/*
 #include "include/amdgpu_dal_power_if.h"
 #include "amdgpu_dm_irq.h"
 */