mdss: mhl3: add null pointer and safety checks to mhl

Add NULL checks and array bounds checks to ensure
that no dereferencing of invalid data occurs in
the MHL driver.

Change-Id: I855412b4603cbe416d901be88a24a28dc6770d2c
Signed-off-by: Casey Piper <cpiper@codeaurora.org>

drivers/video/fbdev/msm/mhl3/mhl_linux_tx.c

@@ -331,7 +331,7 @@ ssize_t send_scratch_pad(struct device *dev, struct device_attribute *attr,
 	 * Parse the input string and extract the scratch pad register selection
 	 * parameters
 	 */
-	str = strstr(pinput, "offset=");
+	str = strnstr(pinput, "offset=", count);
 	if (str != NULL) {
 		str += 7;
 		status = si_strtoul(&str, 0, &offset);
@@ -3067,7 +3067,7 @@ void mhl_event_notify(struct mhl_dev_context *dev_context, u32 event,
 			"MHLEVENT=SPAD_CHG length=0x%02x data=", length);
 
 		count = 0;
-		while (idx < MAX_EVENT_STRING_LEN) {
+		while (buf && idx < MAX_EVENT_STRING_LEN) {
 			if (count >= length)
 				break;
 

drivers/video/fbdev/msm/mhl3/mhl_supp.c

@@ -484,12 +484,14 @@ void si_mhl_tx_push_block_transactions(struct mhl_dev_context *dev_context)
 		req->payload->hdr_and_burst_id.tport_hdr.length_remaining =
 		    req->sub_payload_size;
 		req->count = payload_size;
-		/* The driver layer will fill in the rx_unload_ack field */
+		if (req->count < EMSC_PAYLOAD_LEN) {
+			/* The driver layer will fill */
+			/* in the rx_unload_ack field */
 			mhl_tx_drv_send_block((struct drv_hw_context *)
 					      (&dev_context->drv_context), req);
 			/* return request to free list */
 			return_block_queue_entry(dev_context, req);
-
+		}
 	}
 	if (NULL == dev_context->block_protocol.marshalling_req) {
 		/* now start a new marshalling request */
@@ -1337,7 +1339,7 @@ void si_mhl_tx_drive_states(struct mhl_dev_context *dev_context)
 					    next_req;
 				}
 
-			} while (ret_val);
+			} while (ret_val && req);
 			break;
 		case MHL_MSC_MSG:
 			if (MHL_MSC_MSG_RAP == req->msg_data[0]) {

drivers/video/fbdev/msm/mhl3/si_8620_drv.c

@@ -858,6 +858,11 @@ drain_rfifo:
 	MHL_TX_DBG_ERR("Draining %d bytes from RFIFO\n", data_len);
 
 	pbit_bucket = kmalloc(data_len, GFP_KERNEL);
+	if (!pbit_bucket) {
+		MHL_TX_DBG_ERR("Failed to allocate %d bytes for pbit bucket\n",
+							data_len);
+		goto done_emsc;
+	}
 	if (use_spi) {
 		mhl_tx_read_spi_emsc(hw_context, data_len, pbit_bucket);
 	} else {
@@ -1831,8 +1836,10 @@ void mhl_tx_drv_send_block(struct drv_hw_context *hw_context,
 	if (use_spi) {
 		mhl_tx_write_block_spi_emsc(hw_context, req);
 	} else {
-		mhl_tx_write_reg_block(hw_context, REG_EMSC_XMIT_WRITE_PORT,
-			req->count, &req->payload->as_bytes[0]);
+		if (req->count < EMSC_PAYLOAD_LEN)
+			mhl_tx_write_reg_block(hw_context,
+				REG_EMSC_XMIT_WRITE_PORT, req->count,
+				&req->payload->as_bytes[0]);
 	}
 }
 
@@ -2258,6 +2265,10 @@ uint8_t si_mhl_tx_drv_send_cbus_command(struct drv_hw_context *hw_context,
 		     req->burst_offset, req->length);
 		hw_context->hawb_write_pending = true;
 		enable_gen2_write_burst_xmit(hw_context);
+		if (req->length > CBUS_REQ_MSG_DATA_LEN) {
+			ret_val = -EINVAL;
+			break;
+		}
 		mhl_tx_write_reg_block(hw_context,
 				       REG_MDT_XMIT_WRITE_PORT,
 				       req->length, req->msg_data);

drivers/video/fbdev/msm/mhl3/si_mhl2_edid_3d.c

@@ -1923,7 +1923,8 @@ static void si_mhl_tx_prune_edid(struct edid_3d_data_t *mhl_edid_3d_data)
 		}
 	}
 
-	if (mhl_edid_3d_data->parse_data.p_three_d) {
+	if (mhl_edid_3d_data->parse_data.p_three_d &&
+				mhl_edid_3d_data->parse_data.p_HDMI_vsdb) {
 		uint8_t num_3D_structure_bytes_pruned = 0;
 		union {
 			union _3D_structure_and_detail_entry_u *p_3D;
@@ -4288,7 +4289,10 @@ int si_mhl_tx_get_num_cea_861_extensions(void *context, uint8_t block_number)
 	uint8_t limit_blocks = sizeof(mhl_edid_3d_data->EDID_block_data) /
 	    EDID_BLOCK_SIZE;
 
-	uint8_t *pb_data =
+	uint8_t *pb_data;
+	if (block_number > NUM_VIDEO_DATA_BLOCKS_LIMIT)
+		return ne_BAD_DATA;
+	pb_data =
 	    &mhl_edid_3d_data->EDID_block_data[EDID_BLOCK_SIZE * block_number];
 
 	MHL_TX_EDID_INFO("block number:%d pb_data:%x\n", block_number, pb_data);

drivers/video/fbdev/msm/mhl3/si_mhl_tx_hw_drv_api.h

@@ -16,6 +16,8 @@
 #if !defined(SI_MHL_TX_DRV_API_H)
 #define SI_MHL_TX_DRV_API_H
 
+#define CBUS_REQ_MSG_DATA_LEN 16
+#define EMSC_PAYLOAD_LEN 256
 /*
  * Structure to hold command details from upper layer to CBUS module
  */
@@ -34,7 +36,7 @@ struct cbus_req {
 	uint8_t reg_data;
 	uint8_t burst_offset;	/* register offset */
 	uint8_t length;		/* Only applicable to write burst */
-	uint8_t msg_data[16];	/* scratch pad data area. */
+	uint8_t msg_data[CBUS_REQ_MSG_DATA_LEN]; /* scratch pad data area. */
 	const char *function;
 	int line;
 	int sequence;
@@ -53,7 +55,7 @@ struct SI_PACK_THIS_STRUCT tport_hdr_and_burst_id_t {
 };
 union SI_PACK_THIS_STRUCT emsc_payload_t {
 	struct SI_PACK_THIS_STRUCT tport_hdr_and_burst_id_t hdr_and_burst_id;
-	uint8_t as_bytes[256];
+	uint8_t as_bytes[EMSC_PAYLOAD_LEN];
 };
 
 struct SI_PACK_THIS_STRUCT block_req {