From: Mark Wooding <mdw@distorted.org.uk>
Date: Tue, 19 Sep 2017 09:02:25 +0000 (+0100)
Subject: pathmtu/pathmtu.c (raw): Check the UDP packet signature.
X-Git-Tag: 1.5.0~41^2~37
X-Git-Url: https://www.chiark.greenend.org.uk/ucgi/~mdw/git/tripe/commitdiff_plain/9ad20ce0b9ce760ad86a9a954c9662d8e4a346fe?ds=sidebyside

pathmtu/pathmtu.c (raw): Check the UDP packet signature.
---

diff --git a/pathmtu/pathmtu.c b/pathmtu/pathmtu.c
index 6d988031..f42602e0 100644
--- a/pathmtu/pathmtu.c
+++ b/pathmtu/pathmtu.c
@@ -533,6 +533,7 @@ static int raw_selproc(void *stv, fd_set *fd_in, struct probestate *ps)
   struct ip *ip;
   struct icmp *icmp;
   struct udphdr *udp;
+  const unsigned char *payload;
   ssize_t n;
 
   /* An ICMP packet: see what's inside. */
@@ -565,6 +566,9 @@ static int raw_selproc(void *stv, fd_set *fd_in, struct probestate *ps)
       goto skip_icmp;
     n -= sizeof(*udp);
 
+    payload = (const unsigned char *)(udp + 1);
+    if (!mypacketp(ps, payload, n)) goto skip_icmp;
+
     if (icmp->icmp_code == ICMP_UNREACH_PORT) return (RC_HIGHER);
     else if (icmp->icmp_code != ICMP_UNREACH_NEEDFRAG) goto skip_icmp;
     else if (icmp->icmp_nextmtu) return (htons(icmp->icmp_nextmtu));