Don't propagate StrictMode over one-way Binder calls.

This was causing stack stitching problems where a one-way call with
violations followed by a two-way call without violations was getting
the previous one-way call's violation stack stitched on to the second
caller's stack.

The solution is a little more indirect than I would've liked
(preserving the binder's onTransact flags until enforceInterface) but
was seemingly necessary to work without changing the AIDL compiler.
It should also be sufficiently cheap, since no new calls to
thread-local IPCThreadState lookups were required.  The additional
work is just same-thread getter/setters on the existing
IPCThreadState.

Change-Id: I4b6db1d445c56e868e6d0d7be3ba6849f4ef23ae

1 files changed, 10 insertions, 1 deletions

diff --git a/libs/binder/Parcel.cpp b/libs/binder/Parcel.cpp
index 18f75df..f329ac4 100644
--- a/libs/binder/Parcel.cpp
+++ b/libs/binder/Parcel.cpp
@@ -464,7 +464,16 @@ bool Parcel::enforceInterface(const String16& interface,
     if (threadState == NULL) {
         threadState = IPCThreadState::self();
     }
-    threadState->setStrictModePolicy(strictPolicy);
+    if ((threadState->getLastTransactionBinderFlags() &
+         IBinder::FLAG_ONEWAY) != 0) {
+      // For one-way calls, the callee is running entirely
+      // disconnected from the caller, so disable StrictMode entirely.
+      // Not only does disk/network usage not impact the caller, but
+      // there's no way to commuicate back any violations anyway.
+      threadState->setStrictModePolicy(0);
+    } else {
+      threadState->setStrictModePolicy(strictPolicy);
+    }
     const String16 str(readString16());
     if (str == interface) {
         return true;