diag: Prevent out-of-bound access while processing userspace data

Proper buffer length checks are missing in diagchar_write
handlers for userspace data while processing the same buffer.

Change-Id: I5b8095766e09c22f164398089505fe827fee8b54
Signed-off-by: Hardik Arya <harya@codeaurora.org>

drivers/char/diag/diag_masks.c

@@ -643,7 +643,7 @@ static int diag_cmd_get_build_mask(unsigned char *src_buf, int src_len,
 	struct diag_build_mask_req_t *req = NULL;
 	struct diag_msg_build_mask_t rsp;
 
-	if (!src_buf || !dest_buf || src_len <= 0 || dest_len <= 0 ||
+	if (!src_buf || !dest_buf || dest_len <= 0 ||
 		src_len < sizeof(struct diag_build_mask_req_t)) {
 		pr_err("diag: Invalid input in %s, src_buf: %pK, src_len: %d, dest_buf: %pK, dest_len: %d\n",
 		       __func__, src_buf, src_len, dest_buf, dest_len);
@@ -705,7 +705,7 @@ static int diag_cmd_get_msg_mask(unsigned char *src_buf, int src_len,
 	info = diag_md_session_get_pid(pid);
 
 	mask_info = (!info) ? &msg_mask : info->msg_mask;
-	if (!src_buf || !dest_buf || src_len <= 0 || dest_len <= 0 ||
+	if (!src_buf || !dest_buf || dest_len <= 0 ||
 	    !mask_info || (src_len < sizeof(struct diag_build_mask_req_t))) {
 		pr_err("diag: Invalid input in %s, src_buf: %pK, src_len: %d, dest_buf: %pK, dest_len: %d, mask_info: %pK\n",
 		       __func__, src_buf, src_len, dest_buf, dest_len,
@@ -787,8 +787,8 @@ static int diag_cmd_set_msg_mask(unsigned char *src_buf, int src_len,
 	info = diag_md_session_get_pid(pid);
 
 	mask_info = (!info) ? &msg_mask : info->msg_mask;
-	if (!src_buf || !dest_buf || src_len <= 0 || dest_len <= 0 ||
-	    !mask_info) {
+	if (!src_buf || !dest_buf || dest_len <= 0 || !mask_info ||
+		(src_len < sizeof(struct diag_msg_build_mask_t))) {
 		pr_err("diag: Invalid input in %s, src_buf: %pK, src_len: %d, dest_buf: %pK, dest_len: %d, mask_info: %pK\n",
 		       __func__, src_buf, src_len, dest_buf, dest_len,
 		       mask_info);
@@ -872,7 +872,9 @@ static int diag_cmd_set_msg_mask(unsigned char *src_buf, int src_len,
 			break;
 		}
 		mask_size = mask_size * sizeof(uint32_t);
-		memcpy(mask->ptr + offset, src_buf + header_len, mask_size);
+		if (mask_size && src_len >= header_len + mask_size)
+			memcpy(mask->ptr + offset, src_buf + header_len,
+				mask_size);
 		mutex_unlock(&mask->lock);
 		mask_info->status = DIAG_CTRL_MASK_VALID;
 		break;
@@ -929,8 +931,8 @@ static int diag_cmd_set_all_msg_mask(unsigned char *src_buf, int src_len,
 	info = diag_md_session_get_pid(pid);
 
 	mask_info = (!info) ? &msg_mask : info->msg_mask;
-	if (!src_buf || !dest_buf || src_len <= 0 || dest_len <= 0 ||
-	    !mask_info) {
+	if (!src_buf || !dest_buf || dest_len <= 0 || !mask_info ||
+		(src_len < sizeof(struct diag_msg_config_rsp_t))) {
 		pr_err("diag: Invalid input in %s, src_buf: %pK, src_len: %d, dest_buf: %pK, dest_len: %d, mask_info: %pK\n",
 		       __func__, src_buf, src_len, dest_buf, dest_len,
 		       mask_info);
@@ -1049,8 +1051,8 @@ static int diag_cmd_update_event_mask(unsigned char *src_buf, int src_len,
 	mutex_lock(&driver->md_session_lock);
 	info = diag_md_session_get_pid(pid);
 	mask_info = (!info) ? &event_mask : info->event_mask;
-	if (!src_buf || !dest_buf || src_len <= 0 || dest_len <= 0 ||
-	    !mask_info) {
+	if (!src_buf || !dest_buf || dest_len <= 0 || !mask_info ||
+		src_len < sizeof(struct diag_event_mask_config_t)) {
 		pr_err("diag: Invalid input in %s, src_buf: %pK, src_len: %d, dest_buf: %pK, dest_len: %d, mask_info: %pK\n",
 		       __func__, src_buf, src_len, dest_buf, dest_len,
 		       mask_info);
@@ -1073,7 +1075,8 @@ static int diag_cmd_update_event_mask(unsigned char *src_buf, int src_len,
 	}
 
 	mutex_lock(&mask_info->lock);
-	memcpy(mask_info->ptr, src_buf + header_len, mask_len);
+	if (src_len >= header_len + mask_len)
+		memcpy(mask_info->ptr, src_buf + header_len, mask_len);
 	mask_info->status = DIAG_CTRL_MASK_VALID;
 	mutex_unlock(&mask_info->lock);
 	mutex_unlock(&driver->md_session_lock);
@@ -1117,8 +1120,8 @@ static int diag_cmd_toggle_events(unsigned char *src_buf, int src_len,
 	mutex_lock(&driver->md_session_lock);
 	info = diag_md_session_get_pid(pid);
 	mask_info = (!info) ? &event_mask : info->event_mask;
-	if (!src_buf || !dest_buf || src_len <= 0 || dest_len <= 0 ||
-	    !mask_info) {
+	if (!src_buf || !dest_buf || src_len <= sizeof(uint8_t) ||
+		dest_len <= 0 || !mask_info) {
 		pr_err("diag: Invalid input in %s, src_buf: %pK, src_len: %d, dest_buf: %pK, dest_len: %d, mask_info: %pK\n",
 		       __func__, src_buf, src_len, dest_buf, dest_len,
 		       mask_info);
@@ -1185,8 +1188,8 @@ static int diag_cmd_get_log_mask(unsigned char *src_buf, int src_len,
 	info = diag_md_session_get_pid(pid);
 
 	mask_info = (!info) ? &log_mask : info->log_mask;
-	if (!src_buf || !dest_buf || src_len <= 0 || dest_len <= 0 ||
-	    !mask_info) {
+	if (!src_buf || !dest_buf || dest_len <= 0 || !mask_info ||
+		src_len < sizeof(struct diag_log_config_req_t)) {
 		pr_err("diag: Invalid input in %s, src_buf: %pK, src_len: %d, dest_buf: %pK, dest_len: %d, mask_info: %pK\n",
 		       __func__, src_buf, src_len, dest_buf, dest_len,
 		       mask_info);
@@ -1329,8 +1332,8 @@ static int diag_cmd_set_log_mask(unsigned char *src_buf, int src_len,
 	info = diag_md_session_get_pid(pid);
 
 	mask_info = (!info) ? &log_mask : info->log_mask;
-	if (!src_buf || !dest_buf || src_len <= 0 || dest_len <= 0 ||
-	    !mask_info) {
+	if (!src_buf || !dest_buf || dest_len <= 0 || !mask_info ||
+		src_len < sizeof(struct diag_log_config_req_t)) {
 		pr_err("diag: Invalid input in %s, src_buf: %pK, src_len: %d, dest_buf: %pK, dest_len: %d, mask_info: %pK\n",
 		       __func__, src_buf, src_len, dest_buf, dest_len,
 		       mask_info);
@@ -1404,7 +1407,7 @@ static int diag_cmd_set_log_mask(unsigned char *src_buf, int src_len,
 			mask->range_tools = mask_size;
 		}
 		req->num_items = mask->num_items_tools;
-		if (mask_size > 0)
+		if (mask_size > 0 && src_len >= read_len + mask_size)
 			memcpy(mask->ptr, src_buf + read_len, mask_size);
 		DIAG_LOG(DIAG_DEBUG_MASKS,
 			 "copying log mask, e %d num %d range %d size %d\n",

drivers/char/diag/diagchar_core.c

@@ -1,4 +1,4 @@
-/* Copyright (c) 2008-2018, The Linux Foundation. All rights reserved.
+/* Copyright (c) 2008-2019, 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
@@ -1187,15 +1187,19 @@ static int diag_process_userspace_remote(int proc, void *buf, int len)
 }
 #endif
 
-static int mask_request_validate(unsigned char mask_buf[])
+static int mask_request_validate(unsigned char mask_buf[], int len)
 {
 	uint8_t packet_id;
 	uint8_t subsys_id;
 	uint16_t ss_cmd;
 
+	if (len <= 0)
+		return 0;
 	packet_id = mask_buf[0];
 
 	if (packet_id == DIAG_CMD_DIAG_SUBSYS_DELAY) {
+		if (len < 2*sizeof(uint8_t) + sizeof(uint16_t))
+			return 0;
 		subsys_id = mask_buf[1];
 		ss_cmd = *(uint16_t *)(mask_buf + 2);
 		switch (subsys_id) {
@@ -1211,6 +1215,8 @@ static int mask_request_validate(unsigned char mask_buf[])
 			return 0;
 		}
 	} else if (packet_id == 0x4B) {
+		if (len < 2*sizeof(uint8_t) + sizeof(uint16_t))
+			return 0;
 		subsys_id = mask_buf[1];
 		ss_cmd = *(uint16_t *)(mask_buf + 2);
 		/* Packets with SSID which are allowed */
@@ -2892,7 +2898,8 @@ static int diag_user_process_raw_data(const char __user *buf, int len)
 	}
 
 	/* Check for proc_type */
-	remote_proc = diag_get_remote(*(int *)user_space_data);
+	if (len >= sizeof(int))
+		remote_proc = diag_get_remote(*(int *)user_space_data);
 	if (remote_proc) {
 		token_offset = sizeof(int);
 		if (len <= MIN_SIZ_ALLOW) {
@@ -2906,7 +2913,7 @@ static int diag_user_process_raw_data(const char __user *buf, int len)
 	}
 	if (driver->mask_check) {
 		if (!mask_request_validate(user_space_data +
-						token_offset)) {
+						token_offset, len)) {
 			pr_alert("diag: mask request Invalid\n");
 			diagmem_free(driver, user_space_data, mempool);
 			user_space_data = NULL;
@@ -2984,7 +2991,7 @@ static int diag_user_process_userspace_data(const char __user *buf, int len)
 	/* Check masks for On-Device logging */
 	if (driver->mask_check) {
 		if (!mask_request_validate(driver->user_space_data_buf +
-					   token_offset)) {
+					   token_offset, len)) {
 			pr_alert("diag: mask request Invalid\n");
 			return -EFAULT;
 		}