dns: keep AddressSanitizer happy

Type: fix

Change-Id: I0ae4071ee317f38daa882fec17087a55afe75d1d
Signed-off-by: Benoît Ganne <bganne@cisco.com>

2 files changed, 23 insertions, 16 deletions

diff --git a/src/plugins/dns/dns.c b/src/plugins/dns/dns.c
index 4a283bf298f..d07a1dac43b 100644
--- a/src/plugins/dns/dns.c
+++ b/src/plugins/dns/dns.c
@@ -38,6 +38,19 @@
 
 dns_main_t dns_main;
 
+/* the cache hashtable expects a NULL-terminated C-string but everywhere else
+ * expects a non-NULL terminated vector... The pattern of adding \0 but hiding
+ * it away drives AddressSanitizer crazy, this helper tries to bring some of
+ * its sanity back
+ */
+static_always_inline void
+dns_terminate_c_string (u8 **v)
+{
+  vec_add1 (*v, 0);
+  vec_dec_len (*v, 1);
+  clib_mem_unpoison (vec_end (*v), 1);
+}
+
 static int
 dns_cache_clear (dns_main_t * dm)
 {
@@ -826,8 +839,8 @@ re_resolve:
   pool_get (dm->entries, ep);
   clib_memset (ep, 0, sizeof (*ep));
 
-  ep->name = format (0, "%s%c", name, 0);
-  vec_set_len (ep->name, vec_len (ep->name) - 1);
+  ep->name = format (0, "%s", name);
+  dns_terminate_c_string (&ep->name);
 
   hash_set_mem (dm->cache_entry_by_name, ep->name, ep - dm->entries);
 
@@ -985,8 +998,7 @@ found_last_request:
   now = vlib_time_now (vm);
   cname = vnet_dns_labels_to_name (rr->rdata, reply, &pos2);
   /* Save the cname */
-  vec_add1 (cname, 0);
-  vec_dec_len (cname, 1);
+  dns_terminate_c_string (&cname);
   ep = pool_elt_at_index (dm->entries, ep_index);
   ep->cname = cname;
   ep->flags |= (DNS_CACHE_ENTRY_FLAG_CNAME | DNS_CACHE_ENTRY_FLAG_VALID);
@@ -1004,8 +1016,7 @@ found_last_request:
 
   clib_memset (next_ep, 0, sizeof (*next_ep));
   next_ep->name = vec_dup (cname);
-  vec_add1 (next_ep->name, 0);
-  vec_dec_len (next_ep->name, 1);
+  dns_terminate_c_string (&next_ep->name);
 
   hash_set_mem (dm->cache_entry_by_name, next_ep->name,
 		next_ep - dm->entries);
@@ -2607,10 +2618,7 @@ test_dns_expire_command_fn (vlib_main_t * vm,
   dns_cache_entry_t *ep;
 
   if (unformat (input, "%v", &name))
-    {
-      vec_add1 (name, 0);
-      vec_dec_len (name, 1);
-    }
+    dns_terminate_c_string (&name);
   else
     return clib_error_return (0, "no name provided");
 
diff --git a/src/plugins/dns/request_node.c b/src/plugins/dns/request_node.c
index 9179bf8dbdd..9e76a56f961 100644
--- a/src/plugins/dns/request_node.c
+++ b/src/plugins/dns/request_node.c
@@ -208,13 +208,7 @@ dns46_request_inline (vlib_main_t * vm,
 
 	  label0 = (u8 *) (d0 + 1);
 
-	  /*
-	   * vnet_dns_labels_to_name produces a non NULL terminated vector
-	   * vnet_dns_resolve_name expects a C-string.
-	   */
 	  name0 = vnet_dns_labels_to_name (label0, (u8 *) d0, (u8 **) & q0);
-	  vec_add1 (name0, 0);
-	  vec_dec_len (name0, 1);
 
 	  t0->request_type = DNS_PEER_PENDING_NAME_TO_IP;
 
@@ -242,6 +236,11 @@ dns46_request_inline (vlib_main_t * vm,
 	    clib_memcpy_fast (t0->dst_address, ip40->src_address.as_u8,
 			      sizeof (ip4_address_t));
 
+	  /*
+	   * vnet_dns_labels_to_name produces a non NULL terminated vector
+	   * vnet_dns_resolve_name expects a C-string.
+	   */
+	  vec_add1 (name0, 0);
 	  vnet_dns_resolve_name (vm, dm, name0, t0, &ep0);
 
 	  if (ep0)