Check that the argument to freeaddrinfo is not NULL. The behavior may be

unspecified and causes a segmentation fault on Android Bionic libc.
Vlatko fixed the bug in his Android binaries and it was first reported
by @alexismm2.

CHANGELOG

@@ -1,5 +1,9 @@
 # Nmap Changelog ($Id$); -*-text-*-
 
+o Added checks that the argument to freeaddrinfo is not NULL, avoiding
+  a segmentation fault on Android and possibly other platforms.
+  Suggested by Vlatko Kosturjak and Alexismm2.
+
 o [Zenmap] Worked around a pycairo bug that prevented saving the
   topology graphic as PNG on Windows: "Error Saving Snapshot:
   Surface.write_to_png takes one argument which must be a filename

TargetGroup.cc

@@ -220,7 +220,8 @@ int TargetGroup::parse_expr(const char * const target_expr, int af) {
           resolvedaddrs.push_back(ss);
         }
       }
-      freeaddrinfo(addrs);
+      if (addrs != NULL)
+        freeaddrinfo(addrs);
 
       if (resolvedaddrs.empty()) {
         error("Failed to resolve given hostname/IP: %s.  Note that you can't use '/mask' AND '1-4,7,100-' style IP ranges", target_net);
@@ -330,7 +331,8 @@ int TargetGroup::parse_expr(const char * const target_expr, int af) {
         resolvedaddrs.push_back(ss);
       }
     }
-    freeaddrinfo(addrs);
+    if (addrs != NULL)
+      freeaddrinfo(addrs);
 
     if (resolvedaddrs.empty()) {
       error("Failed to resolve given IPv6 hostname/IP: %s.  Note that you can't use '/mask' or '[1-4,7,100-]' style ranges for IPv6.", hostexp);

nse_nmaplib.cc

@@ -724,7 +724,8 @@ static int l_resolve(lua_State *L)
     lua_rawseti(L, -2, i++);
   }
 
-  freeaddrinfo(addrs);
+  if (addrs != NULL)
+    freeaddrinfo(addrs);
 
   return 2;
 }

nse_nsock.cc

@@ -576,7 +576,8 @@ static int l_connect (lua_State *L)
       break;
   }
 
-  freeaddrinfo(dest);
+  if (dest != NULL)
+    freeaddrinfo(dest);
   return yield(L, nu, "CONNECT", TO, 0, NULL);
 }
 

tcpip.cc

@@ -357,7 +357,7 @@ const char *inet_socktop(struct sockaddr_storage *ss) {
 /* Tries to resolve the given name (or literal IP) into a sockaddr structure.
    This function calls getaddrinfo and returns the same addrinfo linked list
    that getaddrinfo produces. Returns NULL for any error or failure to resolve.
-   You need to call freeaddrinfo on the result. */
+   You need to call freeaddrinfo on the result if non-NULL. */
 struct addrinfo *resolve_all(char *hostname, int pf)
 {
   struct addrinfo hints;