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Commit cb1ae7bb authored by Hardik Arya's avatar Hardik Arya
Browse files

diag: Validate copying length against source buffer length 



There a possibility of out-of-bound read because of not
validating source buffer length against length that about
to be copied. The patch adds proper check for validating
length before copying data

CRs-Fixed: 2163793
Change-Id: I7c93839d0c4d83024ce23a0ce494d09dd08567a9
Signed-off-by: default avatarHardik Arya <harya@codeaurora.org>
parent 375a78ac

drivers/char/diag/diag_dci.c

+66 −23
Original line number Diff line number Diff line 
/* Copyright (c) 2012-2017, The Linux Foundation. All rights reserved.

/* Copyright (c) 2012-2018, The Linux Foundation. All rights reserved.

 *

 * This program is free software; you can redistribute it and/or modify

 * it under the terms of the GNU General Public License version 2 and
@@ -1108,18 +1108,31 @@ void extract_dci_events(unsigned char *buf, int len, int data_source, int token) 
	struct list_head *start, *temp;

	struct diag_dci_client_tbl *entry = NULL;



	length =  *(uint16_t *)(buf + 1); /* total length of event series */

	if (length == 0) {

		pr_err("diag: Incoming dci event length is invalid\n");

	if (!buf) {

		pr_err("diag: In %s buffer is NULL\n", __func__);

		return;

	}

	/*

	 * Move directly to the start of the event series. 1 byte for

	 * event code and 2 bytes for the length field.

	 * 1 byte for event code and 2 bytes for the length field.

	 * The length field indicates the total length removing the cmd_code

	 * and the lenght field. The event parsing in that case should happen

	 * till the end.

	 */

	if (len < 3) {

		pr_err("diag: In %s invalid len: %d\n", __func__, len);

		return;

	}

	length = *(uint16_t *)(buf + 1); /* total length of event series */

	if ((length == 0) || (len != (length + 3))) {

		pr_err("diag: Incoming dci event length: %d is invalid\n",

			length);

		return;

	}

	/*

	 * Move directly to the start of the event series.

	 * The event parsing should happen from start of event

	 * series till the end.

	 */

	temp_len = 3;

	while (temp_len < length) {

		event_id_packet = *(uint16_t *)(buf + temp_len);
@@ -1136,30 +1149,60 @@ void extract_dci_events(unsigned char *buf, int len, int data_source, int token) 
			 * necessary.

			 */

			timestamp_len = 8;

			memcpy(timestamp, buf + temp_len + 2, timestamp_len);

			if ((temp_len + timestamp_len + 2) <= len)

				memcpy(timestamp, buf + temp_len + 2,

					timestamp_len);

			else {

				pr_err("diag: Invalid length in %s, len: %d, temp_len: %d",

						__func__, len, temp_len);

				return;

			}

		}

		/* 13th and 14th bit represent the payload length */

		if (((event_id_packet & 0x6000) >> 13) == 3) {

			payload_len_field = 1;

			if ((temp_len + timestamp_len + 3) <= len) {

				payload_len = *(uint8_t *)

					(buf + temp_len + 2 + timestamp_len);

			if (payload_len < (MAX_EVENT_SIZE - 13)) {

				/* copy the payload length and the payload */

			} else {

				pr_err("diag: Invalid length in %s, len: %d, temp_len: %d",

						__func__, len, temp_len);

				return;

			}

			if ((payload_len < (MAX_EVENT_SIZE - 13)) &&

			((temp_len + timestamp_len + payload_len + 3) <= len)) {

				/*

				 * Copy the payload length and the payload

				 * after skipping temp_len bytes for already

				 * parsed packet, timestamp_len for timestamp

				 * buffer, 2 bytes for event_id_packet.

				 */

				memcpy(event_data + 12, buf + temp_len + 2 +

							timestamp_len, 1);

				memcpy(event_data + 13, buf + temp_len + 2 +

					timestamp_len + 1, payload_len);

			} else {

				pr_err("diag: event > %d, payload_len = %d\n",

					(MAX_EVENT_SIZE - 13), payload_len);

				pr_err("diag: event > %d, payload_len = %d, temp_len = %d\n",

				(MAX_EVENT_SIZE - 13), payload_len, temp_len);

				return;

			}

		} else {

			payload_len_field = 0;

			payload_len = (event_id_packet & 0x6000) >> 13;

			/* copy the payload */

			/*

			 * Copy the payload after skipping temp_len bytes

			 * for already parsed packet, timestamp_len for

			 * timestamp buffer, 2 bytes for event_id_packet.

			 */

			if ((payload_len < (MAX_EVENT_SIZE - 12)) &&

			((temp_len + timestamp_len + payload_len + 2) <= len))

				memcpy(event_data + 12, buf + temp_len + 2 +

						timestamp_len, payload_len);

			else {

				pr_err("diag: event > %d, payload_len = %d, temp_len = %d\n",

				(MAX_EVENT_SIZE - 12), payload_len, temp_len);

				return;

			}

		}



		/* Before copying the data to userspace, check if we are still
@@ -1277,19 +1320,19 @@ void extract_dci_log(unsigned char *buf, int len, int data_source, int token) 
		pr_err("diag: In %s buffer is NULL\n", __func__);

		return;

	}



	/* The first six bytes for the incoming log packet contains

	 * Command code (2), the length of the packet (2) and the length

	 * of the log (2)

	/*

	 * The first eight bytes for the incoming log packet contains

	 * Command code (2), the length of the packet (2), the length

	 * of the log (2) and log code (2)

	 */

	log_code = *(uint16_t *)(buf + 6);

	read_bytes += sizeof(uint16_t) + 6;

	if (read_bytes > len) {

		pr_err("diag: Invalid length in %s, len: %d, read: %d",

						__func__, len, read_bytes);

	if (len < 8) {

		pr_err("diag: In %s invalid len: %d\n", __func__, len);

		return;

	}



	log_code = *(uint16_t *)(buf + 6);

	read_bytes += sizeof(uint16_t) + 6;



	/* parse through log mask table of each client and check mask */

	mutex_lock(&driver->dci_mutex);

	list_for_each_safe(start, temp, &driver->dci_client_list) {