Fix GetNetworkList() for POSIX to cope with address-less interfaces.

net/base/net_util_posix.cc

 // Copyright (c) 2011 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "net/base/net_util.h"
 
 #include <sys/types.h>
 
 #include "base/eintr_wrapper.h"
 #include "base/file_path.h"
@@ skipping 58 matching lines @@
   base::ThreadRestrictions::AssertIOAllowed();
 
   ifaddrs *ifaddr;
   if (getifaddrs(&ifaddr) < 0) {
     PLOG(ERROR) << "getifaddrs";
     return false;
   }
 
   for (ifaddrs *ifa = ifaddr; ifa != NULL; ifa = ifa->ifa_next) {
     int family = ifa->ifa_addr->sa_family;
+    if (!ifa->ifa_addr)
+      continue;

[wtc, 2011/08/10 19:29:02]

Did you test this patch?  On line 78 you have already
dereferenced ifa->ifa_addr.  The null pointer test needs to
be done the first thing in the for loop's body.

Please also add a comment to explain why ifa->ifa_addr can
be NULL (it is a network interface with no IP address).

Just curious: in that case, does the ifa->ifa_name field
still contain the correct network interface name?

[wtc, 2011/08/10 19:32:22]

I checked the other two getifaddrs calls in net/base/net_util.cc.
They already have this null pointer test.

     if (family == AF_INET || family == AF_INET6) {
       IPEndPoint address;
       std::string name = ifa->ifa_name;
       if (address.FromSockAddr(ifa->ifa_addr,
                                sizeof(ifa->ifa_addr)) &&
           name.substr(0, 2) != "lo") {
         networks->push_back(NetworkInterface(name, address.address()));
       }
     }
   }
 
   freeifaddrs(ifaddr);
 
   return true;
 #endif
 }
 
 }  // namespace net