slip: Drop packets >mtu (SECURITY)

[secnet] / slip.c

diff --git a/slip.c b/slip.c
index 9e63cb3..aed2551 100644 (file)
--- a/slip.c
+++ b/slip.c
@@ -213,6 +213,14 @@ static void userv_deliver_to_kernel(void *sst, struct buffer_if *buf)
 {
     struct userv *st=sst;
 
+    if (buf->size > st->slip.nl.mtu) {
+       Message(M_ERR,"%s: packet of size %"PRIu32" exceeds mtu %"PRIu32":"
+               " cannot be injected into kernel, dropped\n",
+               st->slip.nl.name, buf->size, st->slip.nl.mtu);
+       BUF_FREE(buf);
+       return;
+    }
+
     slip_stuff(&st->slip,buf,st->txfd);
 }