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Merged
gasbytes merged 1 commit into from
Mar 2, 2026
Merged

Validate minimum TCP header length #53

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53 changes: 53 additions & 0 deletions src/test/unit/unit.c
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Original file line number Diff line number Diff line change
Expand Up @@ -13870,6 +13870,58 @@ START_TEST(test_tcp_input_fin_wait_1_fin_payload_ack_mismatch_no_transition)
}
END_TEST

START_TEST(test_tcp_input_header_len_below_min_dropped)
{
struct wolfIP s;
struct tsocket *ts;
uint8_t buf[sizeof(struct wolfIP_tcp_seg) + 4];
struct wolfIP_tcp_seg *seg = (struct wolfIP_tcp_seg *)buf;
uint8_t payload[4] = {1, 2, 3, 4};
uint32_t ack = 100;
uint32_t seq = 100;

wolfIP_init(&s);
mock_link_init(&s);
wolfIP_ipconfig_set(&s, 0x0A000001U, 0xFFFFFF00U, 0);

ts = &s.tcpsockets[0];
memset(ts, 0, sizeof(*ts));
ts->proto = WI_IPPROTO_TCP;
ts->S = &s;
ts->sock.tcp.state = TCP_ESTABLISHED;
ts->sock.tcp.ack = ack;
ts->src_port = 1234;
ts->dst_port = 4321;
ts->local_ip = 0x0A000001U;
ts->remote_ip = 0x0A000002U;
queue_init(&ts->sock.tcp.rxbuf, ts->rxmem, RXBUF_SIZE, ts->sock.tcp.ack);

memset(buf, 0, sizeof(buf));
seg->ip.ver_ihl = 0x45;
seg->ip.ttl = 64;
seg->ip.proto = WI_IPPROTO_TCP;
seg->ip.len = ee16(IP_HEADER_LEN + TCP_HEADER_LEN + sizeof(payload));
seg->ip.src = ee32(ts->remote_ip);
seg->ip.dst = ee32(ts->local_ip);
seg->dst_port = ee16(ts->src_port);
seg->src_port = ee16(ts->dst_port);
seg->seq = ee32(seq);
seg->ack = ee32(ack);
seg->flags = TCP_FLAG_ACK;
seg->hlen = 0; /* invalid: data offset below minimum */
memcpy(seg->data, payload, sizeof(payload));
fix_tcp_checksums(seg);

tcp_input(&s, TEST_PRIMARY_IF, seg,
(uint32_t)(ETH_HEADER_LEN + IP_HEADER_LEN + TCP_HEADER_LEN + sizeof(payload)));

ck_assert_int_eq(ts->sock.tcp.state, TCP_ESTABLISHED);
ck_assert_uint_eq(ts->sock.tcp.ack, ack);
ck_assert_uint_eq(ts->events & CB_EVENT_READABLE, 0);
ck_assert_uint_eq(queue_len(&ts->sock.tcp.rxbuf), 0U);
}
END_TEST

START_TEST(test_tcp_input_fin_wait_2_fin_with_payload_queues)
{
struct wolfIP s;
Expand Down Expand Up @@ -17263,6 +17315,7 @@ Suite *wolf_suite(void)
tcase_add_test(tc_utils, test_tcp_input_fin_wait_1_fin_out_of_order_no_transition);
tcase_add_test(tc_utils, test_tcp_input_fin_wait_1_fin_payload_out_of_order_no_transition);
tcase_add_test(tc_utils, test_tcp_input_fin_wait_1_fin_payload_ack_mismatch_no_transition);
tcase_add_test(tc_utils, test_tcp_input_header_len_below_min_dropped);
tcase_add_test(tc_utils, test_socket_from_fd_invalid);
tcase_add_test(tc_utils, test_socket_from_fd_valid);

Expand Down
4 changes: 4 additions & 0 deletions src/wolfip.c
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Original file line number Diff line number Diff line change
Expand Up @@ -3151,6 +3151,10 @@ static void tcp_input(struct wolfIP *S, unsigned int if_idx,
wolfIP_send_ttl_exceeded(S, if_idx, &tcp->ip);
return;
}
/* Validate minimum TCP header length (data offset). */
if ((tcp->hlen >> 2) < TCP_HEADER_LEN) {
return; /* malformed: TCP header below minimum length */
}
/* Validate TCP header length fits in IP payload */
if (iplen < (uint32_t)(IP_HEADER_LEN + (tcp->hlen >> 2))) {
return; /* malformed: TCP header exceeds IP length */
Expand Down