Don't include the data dir in zygote library paths.

When creating a LoadedApk in a zygote context (app zygote or WebView
zygote), don't add the app's data dir to the list of paths the dynamic
linker is allowed to load libraries from, because the linker's attempt
to canonicalize the path causes SELinux access denials. The process
can't access the data directory at all, so cannot load libraries from
there in any case.

Fixes: 149481620
Test: check for avc denials from webview_zygote
Change-Id: I9aceecaf6067e748cc2251782b0f41661cbb35d8
Merged-In: I9aceecaf6067e748cc2251782b0f41661cbb35d8

core/java/android/app/LoadedApk.java

@@ -797,6 +797,11 @@ public final class LoadedApk {
         makePaths(mActivityThread, isBundledApp, mApplicationInfo, zipPaths, libPaths);
 
         String libraryPermittedPath = mDataDir;
+        if (mActivityThread == null) {
+            // In a zygote context where mActivityThread is null we can't access the app data dir
+            // and including this in libraryPermittedPath would cause SELinux denials.
+            libraryPermittedPath = "";
+        }
 
         if (isBundledApp) {
             // For bundled apps, add the base directory of the app (e.g.,