8429 getallifaddrs dereferences invalid pointer causing SIGSEGV
Reviewed by: Sebastian Wiedenroth <sw@core.io>
Reviewed by: Yuri Pankov <yuripv@gmx.com>
Reviewed by: Toomas Soome <tsoome@me.com>

*** 19,28 ****
--- 19,29 ----
   * CDDL HEADER END
   */
  
  /*
   * Copyright (c) 2010, Oracle and/or its affiliates. All rights reserved.
+  * Copyright 2017 RackTop Systems.
   */
  
  #include <netdb.h>
  #include <nss_dbdefs.h>
  #include <netinet/in.h>
*** 100,109 ****
--- 101,118 ----
          sa_family_t lifr_af;
          int sock4;
          int sock6;
          int err;
  
+         /*
+          * Initialize ifap to NULL so we can safely call freeifaddrs
+          * on it in case of error.
+          */
+         if (ifap == NULL)
+                 return (EINVAL);
+         *ifap = NULL;
+ 
          if ((sock4 = socket(AF_INET, SOCK_DGRAM, 0)) < 0)
                  return (-1);
          if ((sock6 = socket(AF_INET6, SOCK_DGRAM, 0)) < 0) {
                  err = errno;
                  close(sock4);
*** 121,131 ****
           * Loop through the interfaces obtained from SIOCGLIFCOMF
           * and retrieve the addresses, netmask and flags.
           */
          prev = NULL;
          lifrp = buf;
-         *ifap = NULL;
          for (n = 0; n < numifs; n++, lifrp++) {
  
                  /* Prepare for the ioctl call */
                  (void) strncpy(lifrl.lifr_name, lifrp->lifr_name,
                      sizeof (lifrl.lifr_name));
--- 130,139 ----