Fix segfault when dest->mtu is 0.

[oweals/tinc.git] / src / route.c

diff --git a/src/route.c b/src/route.c
index 850a146e496cf3d45ad5a730756e1b3f467185f8..f8b11bb6be7bcf405ec1a3ee7adfefa6f09cb57c 100644 (file)
--- a/src/route.c
+++ b/src/route.c
@@ -581,7 +581,7 @@ static void fragment_ipv4_packet(node_t *dest, vpn_packet_t *packet, length_t et
        ifdebug(TRAFFIC) logger(LOG_INFO, "Fragmenting packet of %d bytes to %s (%s)", packet->len, dest->name, dest->hostname);
 
        offset = packet->data + ether_size + ip_size;
-       maxlen = (dest->mtu - ether_size - ip_size) & ~0x7;
+       maxlen = (MAX(dest->mtu, 590) - ether_size - ip_size) & ~0x7;
        ip_off = ntohs(ip.ip_off);
        origf = ip_off & ~IP_OFFMASK;
        ip_off &= IP_OFFMASK;