heapdump: use appendable file descriptor

For heapdump functionality, there's no need to give apps
readable/writable file descriptors. An append-only file descriptor
is sufficient.

Bug: 20073185
Change-Id: Ib2c42a72b2704db5f1b919c24e33609f7a45e57a

diff --git a/services/core/java/com/android/server/am/ActivityManagerService.java b/services/core/java/com/android/server/am/ActivityManagerService.java
index 18ab3b4..607e09c 100644 (file)
--- a/services/core/java/com/android/server/am/ActivityManagerService.java
+++ b/services/core/java/com/android/server/am/ActivityManagerService.java
@@ -17467,7 +17467,8 @@ public final class ActivityManagerService extends ActivityManagerNative
                                 fd = ParcelFileDescriptor.open(heapdumpFile,
                                         ParcelFileDescriptor.MODE_CREATE |
                                                 ParcelFileDescriptor.MODE_TRUNCATE |
-                                                ParcelFileDescriptor.MODE_READ_WRITE);
+                                                ParcelFileDescriptor.MODE_WRITE_ONLY |
+                                                ParcelFileDescriptor.MODE_APPEND);
                                 IApplicationThread thread = myProc.thread;
                                 if (thread != null) {
                                     try {