Add checks and unit tests for get_interface_address* failure

Ensure that either a valid address is returned in address pointers,
or that the address data is zeroed on error.

Ensure that free_interface_address6_list handles NULL lists.

Add unit tests for get_interface_address* failure cases.

Fixes bug #17173.
Patch by fk/teor, not in any released version of tor.

1 files changed, 16 insertions, 8 deletions

diff --git a/src/common/address.c b/src/common/address.c
index fc85f8eba2..cfa8fd1dca 100644
--- a/src/common/address.c
+++ b/src/common/address.c
@@ -1506,8 +1506,8 @@ get_interface_addresses_ioctl(int severity)
  * Return a new smartlist of tor_addr_t on success, and NULL on failure.
  * (An empty smartlist indicates that we successfully learned that we have no
  * addresses.)  Log failure messages at <b>severity</b>. */
-STATIC smartlist_t *
-get_interface_addresses_raw(int severity)
+MOCK_IMPL(smartlist_t *,
+get_interface_addresses_raw,(int severity))
 {
   smartlist_t *result = NULL;
 #if defined(HAVE_IFADDRS_TO_SMARTLIST)
@@ -1547,10 +1547,10 @@ tor_addr_is_multicast(const tor_addr_t *a)
  * UDP socket trickery. Only look for address of given <b>family</b>.
  * Set result to *<b>addr</b>. Return 0 on success, -1 on failure.
  */
-STATIC int
-get_interface_address6_via_udp_socket_hack(int severity,
-                                           sa_family_t family,
-                                           tor_addr_t *addr)
+MOCK_IMPL(int,
+get_interface_address6_via_udp_socket_hack,(int severity,
+                                            sa_family_t family,
+                                            tor_addr_t *addr))
 {
   struct sockaddr_storage my_addr, target_addr;
   int sock=-1, r=-1;
@@ -1614,6 +1614,8 @@ get_interface_address6_via_udp_socket_hack(int severity,
  err:
   if (sock >= 0)
     tor_close_socket(sock);
+  if (r == -1)
+    memset(addr, 0, sizeof(tor_addr_t));
   return r;
 }
 
@@ -1632,6 +1634,8 @@ get_interface_address6,(int severity, sa_family_t family, tor_addr_t *addr))
   int rv = -1;
   tor_assert(addr);
 
+  memset(addr, 0, sizeof(tor_addr_t));
+
   /* Get a list of public or internal IPs in arbitrary order */
   addrs = get_interface_address6_list(severity, family, 1);
 
@@ -1656,8 +1660,10 @@ get_interface_address6,(int severity, sa_family_t family, tor_addr_t *addr))
 void
 free_interface_address6_list(smartlist_t *addrs)
 {
-  SMARTLIST_FOREACH(addrs, tor_addr_t *, a, tor_free(a));
-  smartlist_free(addrs);
+  if (addrs != NULL) {
+    SMARTLIST_FOREACH(addrs, tor_addr_t *, a, tor_free(a));
+    smartlist_free(addrs);
+  }
 }
 
 /** Return a smartlist of the IP addresses of type family from all interfaces
@@ -1975,6 +1981,8 @@ get_interface_address,(int severity, uint32_t *addr))
   tor_addr_t local_addr;
   int r;
 
+  memset(addr, 0, sizeof(uint32_t));
+
   r = get_interface_address6(severity, AF_INET, &local_addr);
   if (r>=0)
     *addr = tor_addr_to_ipv4h(&local_addr);