Fixed buffer overflows with safe str search

1. Detected a lot of memory errors using address sanitizer
and ndpi-scapy tool.

2. Added ndpi_match_prefix function that compares strings
with taking care of payload packet len. Almost drop-in
replacement for match_first_bytes function.

3. Replaced unsafe match_first_bytes usage with a ndpi_match_prefix
and additional length checks.

1 files changed, 2 insertions, 0 deletions

diff --git a/src/lib/protocols/rtp.c b/src/lib/protocols/rtp.c
index 17744ed95..9bcaec941 100644
--- a/src/lib/protocols/rtp.c
+++ b/src/lib/protocols/rtp.c
@@ -73,6 +73,8 @@ static void ndpi_rtp_search(struct ndpi_detection_module_struct *ndpi_struct,
 			    struct ndpi_flow_struct *flow,
 			    const u_int8_t * payload, const u_int16_t payload_len)
 {
+  if (payload_len < 2)
+    return;
   //struct ndpi_packet_struct *packet = &flow->packet;
   u_int8_t payloadType, payload_type = payload[1] & 0x7F;
   u_int32_t *ssid = (u_int32_t*)&payload[8];