File libslirp-CVE-2021-3593.patch of Package libslirp.25314

diff --git a/src/udp6.c b/src/udp6.c
index 18ce998d7c156ffb1f9609d0d63a72e567d03f72..efeac5c19ad03dbf0af59a6a2a4f6ac0c9a5c939 100644
--- a/src/udp6.c
+++ b/src/udp6.c
@@ -31,7 +31,10 @@ void udp6_input(struct mbuf *m)
     ip = mtod(m, struct ip6 *);
     m->m_len -= iphlen;
     m->m_data += iphlen;
-    uh = mtod(m, struct udphdr *);
+    uh = mtod_check(m, sizeof(struct udphdr));
+    if (uh == NULL) {
+        goto bad;
+    }
     m->m_len += iphlen;
     m->m_data -= iphlen;