[5/6] batctl: tcpdump: Add missing ICMPv6 Neighbor Solicit length check

Message ID 20240127-tcpdump_fuzzing-v1-5-fbc1e1d3fec1@narfation.org (mailing list archive)
State Accepted, archived
Delegated to: Simon Wunderlich
Series batctl: tcpdump: Fix problems detected during fuzzing |

Commit Message

Sven Eckelmann Jan. 27, 2024, 12:49 p.m. UTC
  dump_ipv6() is doing a length check for the original ICMPv6 header length.
But the neighbor solicitation (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: 35b37756f4a3 ("add IPv6 support to tcpdump parser")
Cc: Marco Dalla Torre <marco.dallato@gmail.com>
Signed-off-by: Sven Eckelmann <sven@narfation.org>
 tcpdump.c | 2 ++
 1 file changed, 2 insertions(+)


diff --git a/tcpdump.c b/tcpdump.c
index 2ae3909..c253755 100644
--- a/tcpdump.c
+++ b/tcpdump.c
@@ -652,6 +652,8 @@  static void dump_ipv6(unsigned char *packet_buff, ssize_t buff_len,
 			       (size_t)buff_len - sizeof(struct icmp6_hdr));
+			LEN_CHECK((size_t)buff_len - (size_t)(sizeof(struct ip6_hdr)),
+				  sizeof(*nd_neigh_sol), "ICMPv6 Neighbor Solicitation");
 			nd_neigh_sol = (struct nd_neighbor_solicit *)icmphdr;
 			inet_ntop(AF_INET6, &(nd_neigh_sol->nd_ns_target),
 				  nd_nas_target, 40);