[PATCH 03/29] drm/amd/display: Fix invalid DPIA AUX reply causing system hang

[Tom Chung]

From: Stylon Wang <stylon.wang at amd.com>

[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 <Roman.Li at amd.com>
Acked-by: Tom Chung <chiahsuan.chung at amd.com>
Signed-off-by: Stylon Wang <stylon.wang at amd.com>
Cc: stable at vger.kernel.org #6.0.x
---
 .../gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 20 +++++++++++++++++++
 .../gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.h |  6 ------
 2 files changed, 20 insertions(+), 6 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 4d90c5415d5c..e15913285250 100644
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
@@ -144,6 +144,14 @@ MODULE_FIRMWARE(FIRMWARE_NAVI12_DMCU);
 /* 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
  *
@@ -10215,6 +10223,8 @@ static int amdgpu_dm_set_dmub_async_sync_status(bool is_cmd_aux,
 			*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;
 		}
@@ -10262,6 +10272,16 @@ int amdgpu_dm_process_dmub_aux_transfer_sync(bool is_cmd_aux, struct dc_context
 			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);
 			}
diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.h b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.h
index b618b2586e7b..83436ef3b26b 100644
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.h
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.h
@@ -50,12 +50,6 @@
 
 #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"
-- 
2.25.1