Subject: batctl: tcpdump: Add missing throughput header length check
From: Sven Eckelmann <[email-masked]>
Date: Sat, 27 Jan 2024 13:49:00 +0100

dump_batman_icmp() is only doing a length check for the original ICMP
packet length. But the throughput packet (which is also handled by this
function) is accessed without doing an additional length check. So it is
possible that it tries to read outside of the received data.

Fixes: f109b3473f86 ("batctl: introduce throughput meter support")
Signed-off-by: Sven Eckelmann <[email-masked]>
Origin: upstream, https://git.open-mesh.org/batctl.git/commit/189b66496309bc1a54b4821292da2428de8ceb1c

--- a/tcpdump.c
+++ b/tcpdump.c
@@ -863,7 +863,6 @@ static void dump_batman_icmp(unsigned ch
 	LEN_CHECK((size_t)buff_len - sizeof(struct ether_header), sizeof(struct batadv_icmp_packet), "BAT ICMP");
 
 	icmp_packet = (struct batadv_icmp_packet *)(packet_buff + sizeof(struct ether_header));
-	tp = (struct batadv_icmp_tp_packet *)icmp_packet;
 
 	if (!time_printed)
 		print_time();
@@ -894,6 +893,10 @@ static void dump_batman_icmp(unsigned ch
 			(size_t)buff_len - sizeof(struct ether_header));
 		break;
 	case BATADV_TP:
+		LEN_CHECK((size_t)buff_len - sizeof(struct ether_header), sizeof(*tp), "BAT TP");
+
+		tp = (struct batadv_icmp_tp_packet *)icmp_packet;
+
 		printf("%s: ICMP TP type %s (%hhu), id %hhu, seq %u, ttl %2d, v %d, length %zu\n",
 		       name, tp->subtype == BATADV_TP_MSG ? "MSG" :
 			     tp->subtype == BATADV_TP_ACK ? "ACK" : "N/A",