2.4.27

 net

 ipv4

diff -urN linux-2.4.26/net/ipv4/devinet.c linux-2.4.27/net/ipv4/devinet.c
--- linux-2.4.26/net/ipv4/devinet.c   2004-04-14 06:05:41.000000000 -0700
+++ linux-2.4.27/net/ipv4/devinet.c   2004-08-07 16:26:06.828436107 -0700
@@ -662,7 +662,23 @@
          if (ifa->ifa_mask != sin->sin_addr.s_addr) {
             inet_del_ifa(in_dev, ifap, 0);
             ifa->ifa_mask = sin->sin_addr.s_addr;
-            ifa->ifa_prefixlen = inet_mask_len(ifa->ifa_mask);
+            ifa->ifa_prefixlen =
+               inet_mask_len(ifa->ifa_mask);
+
+            /* See if current broadcast address matches
+             * with current netmask, then recalculate
+             * the broadcast address. Otherwise it's a
+             * funny address, so don't touch it since
+             * the user seems to know what (s)he's doing...
+             */
+            if ((dev->flags & IFF_BROADCAST) &&
+                (ifa->ifa_prefixlen < 31) &&
+                (ifa->ifa_broadcast ==
+                 (ifa->ifa_local|~ifa->ifa_mask))) {
+               ifa->ifa_broadcast =
+                  (ifa->ifa_local |
+                   ~sin->sin_addr.s_addr);
+            }
             inet_insert_ifa(ifa);
          }
          break;