slirp: Don't crash on packets from 0.0.0.0/8.

LWIP can generate packets with a source of 0.0.0.0, which triggers an
assertion failure in arp_table_add().  Instead of crashing, simply return
to avoid adding an invalid ARP table entry.

Signed-off-by: Nickolai Zeldovich <nickolai@csail.mit.edu>
Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>

diff --git a/slirp/arp_table.c b/slirp/arp_table.c
index 5d7b8ac..bf698c1 100644 (file)
--- a/slirp/arp_table.c
+++ b/slirp/arp_table.c
@@ -38,7 +38,9 @@ void arp_table_add(Slirp *slirp, uint32_t ip_addr, uint8_t ethaddr[ETH_ALEN])
                 ethaddr[3], ethaddr[4], ethaddr[5]));
 
     /* Check 0.0.0.0/8 invalid source-only addresses */
-    assert((ip_addr & htonl(~(0xf << 28))) != 0);
+    if ((ip_addr & htonl(~(0xf << 28))) == 0) {
+        return;
+    }
 
     if (ip_addr == 0xffffffff || ip_addr == broadcast_addr) {
         /* Do not register broadcast addresses */