Merge pull request #11830 from apolcyn/fix_credential_compose_leaks_master

Fix ruby memory leaks when composing credentials, noticed with asan
diff --git a/src/ruby/ext/grpc/rb_call_credentials.c b/src/ruby/ext/grpc/rb_call_credentials.c
index 95e01a2..17083dd 100644
--- a/src/ruby/ext/grpc/rb_call_credentials.c
+++ b/src/ruby/ext/grpc/rb_call_credentials.c
@@ -239,6 +239,7 @@
                                               VALUE self) {
   grpc_call_credentials *creds;
   grpc_call_credentials *other;
+  grpc_call_credentials *prev = NULL;
   VALUE mark;
   if (argc == 0) {
     return self;
@@ -249,6 +250,10 @@
     rb_ary_push(mark, argv[i]);
     other = grpc_rb_get_wrapped_call_credentials(argv[i]);
     creds = grpc_composite_call_credentials_create(creds, other, NULL);
+    if (prev != NULL) {
+      grpc_call_credentials_release(prev);
+    }
+    prev = creds;
   }
   return grpc_rb_wrap_call_credentials(creds, mark);
 }
diff --git a/src/ruby/ext/grpc/rb_channel_credentials.c b/src/ruby/ext/grpc/rb_channel_credentials.c
index 07935a1..83601ca 100644
--- a/src/ruby/ext/grpc/rb_channel_credentials.c
+++ b/src/ruby/ext/grpc/rb_channel_credentials.c
@@ -184,6 +184,7 @@
                                                  VALUE self) {
   grpc_channel_credentials *creds;
   grpc_call_credentials *other;
+  grpc_channel_credentials *prev = NULL;
   VALUE mark;
   if (argc == 0) {
     return self;
@@ -195,6 +196,11 @@
     rb_ary_push(mark, argv[i]);
     other = grpc_rb_get_wrapped_call_credentials(argv[i]);
     creds = grpc_composite_channel_credentials_create(creds, other, NULL);
+    if (prev != NULL) {
+      grpc_channel_credentials_release(prev);
+    }
+    prev = creds;
+
     if (creds == NULL) {
       rb_raise(rb_eRuntimeError,
                "Failed to compose channel and call credentials");