Commit 6e4e03ed authored Nov 15, 2014 by riddle_hsu Committed by Steve Kondik Jan 28, 2015

[ActivityManager] Ensure provider external access count will be released.

Sympton: Oom-adj of provider process will be always 0.

Root Cause: Exception happend in openContentUri
may not call removeContentProviderExternalUnchecked.

Flow:
application [MediaPlayer.setDataSource(Context context, Uri uri)]
    uri is invalid, IOException will be caught and below log will appear:
    "Couldn't open file on client side, trying server side"
    Continue to call setDataSource(String path, Map<String, String> headers)
 ->mediaserver [MediaPlayerService::Client::setDataSource]
    setDataSource(httpService, url, headers) calls openContentProviderFile
 ->system_server (ActivityManagerService) [openContentUri]
    Increase externalProcessNoHandleCount for media provider.
    Call [openFile] to media provider.
 ->android.process.media [check permission for openFile]
    enforceReadPermissionInner
 ->system_server [checkComponentPermission]
    Use mediaserver's uid to check READ_EXTERNAL_STORAGE
      -> not granted due to it is pure native process, not a known package.
    Throw security exception then the flow of openContentUri is broke.
    And externalProcessNoHandleCount is unable to decrease.

Application sample code:
 String invalidId = "54321";
 Uri externalUri = MediaStore.Files.getContentUri("external");
 Uri uri = Uri.withAppendedPath(externalUri, invalidId);
 mediaPlayer.setDataSource(mContext, uri);

Solution: Move removeContentProviderExternalUnchecked to finally block.

Change-Id: I75eec1f9631e9c6bb18449946d707d51ac21e8a7

parent 63da2824

services/core/java/com/android/server/am/ActivityManagerService.java

+2 −3

Original line number	Diff line number	Diff line
		@@ -10171,10 +10171,9 @@ public final class ActivityManagerService extends ActivityManagerNative
		} finally {
		// Ensure that whatever happens, we clean up the identity state
		sCallerIdentity.remove();
		}

		// We've got the fd now, so we're done with the provider.
		// Ensure we're done with the provider.
		removeContentProviderExternalUnchecked(name, null, userId);
		}
		} else {
		Slog.d(TAG, "Failed to get provider for authority '" + name + "'");
		}