[mojo-edk] Invalidate message handle when rewrite fails

mojo/edk/system/channel.cc

Index: mojo/edk/system/channel.cc
diff --git a/mojo/edk/system/channel.cc b/mojo/edk/system/channel.cc
index a03668ba1af72f281f72889555ddc4a104c8f35c..7cef6d4da0e12bb1c1c624a8668fb8491c3d7a42 100644
--- a/mojo/edk/system/channel.cc
+++ b/mojo/edk/system/channel.cc
@@ -331,15 +331,23 @@ bool Channel::Message::RewriteHandles(base::ProcessHandle from_process,
       DLOG(ERROR) << "Refusing to duplicate invalid handle.";
       continue;
     }
+    CHECK_NE(handles[i].handle, INVALID_HANDLE_VALUE);

[Ken Rockot(use gerrit already), 2016/05/03 16:46:49]

Just noticing that this can't be reached given the test above. It should be OK
for an outgoing message to contain invalid handles as long as we don't try to
dupe them.

     DCHECK_EQ(handles[i].owning_process, from_process);
     BOOL result = DuplicateHandle(
         from_process, handles[i].handle, to_process,
         &handles[i].handle, 0, FALSE,
         DUPLICATE_SAME_ACCESS | DUPLICATE_CLOSE_SOURCE);
-    if (result)
+    if (result) {
       handles[i].owning_process = to_process;
-    else
+    } else {
       success = false;
+
+      // If handle duplication fails, the source handle will already be closed
+      // due to DUPLICATE_CLOSE_SOURCE. Replace the handle in the message with
+      // an invalid handle.
+      handles[i].handle = INVALID_HANDLE_VALUE;
+      handles[i].owning_process = base::GetCurrentProcessHandle();
+    }
   }
   return success;
 }