Merge "[RESTRICT AUTOMERGE][pm] prevent system app downgrades of versions lower than preload" into sc-v2-dev

services/core/java/com/android/server/pm/PackageManagerService.java

@@ -26844,10 +26844,10 @@ public class PackageManagerService extends IPackageManager.Stub
             // will be null whereas dataOwnerPkg will contain information about the package
             // which was uninstalled while keeping its data.
             AndroidPackage dataOwnerPkg = mPackages.get(packageName);
+            PackageSetting dataOwnerPs = mSettings.getPackageLPr(packageName);
             if (dataOwnerPkg  == null) {
-                PackageSetting ps = mSettings.getPackageLPr(packageName);
+                if (dataOwnerPs != null) {
-                if (ps != null) {
+                    dataOwnerPkg = dataOwnerPs.getPkg();
-                    dataOwnerPkg = ps.pkg;
                 }
             }
 
@@ -26871,12 +26871,30 @@ public class PackageManagerService extends IPackageManager.Stub
             if (dataOwnerPkg != null) {
                 if (!PackageManagerServiceUtils.isDowngradePermitted(installFlags,
                         dataOwnerPkg.isDebuggable())) {
+                    // Downgrade is not permitted; a lower version of the app will not be allowed
                     try {
                         checkDowngrade(dataOwnerPkg, pkgLite);
                     } catch (PackageManagerException e) {
                         Slog.w(TAG, "Downgrade detected: " + e.getMessage());
                         return PackageManager.INSTALL_FAILED_VERSION_DOWNGRADE;
                     }
+                } else if (dataOwnerPs.isSystem()) {
+                    // Downgrade is permitted, but system apps can't be downgraded below
+                    // the version preloaded onto the system image
+                    final PackageSetting disabledPs = mSettings.getDisabledSystemPkgLPr(
+                            dataOwnerPs);
+                    if (disabledPs != null) {
+                        dataOwnerPkg = disabledPs.getPkg();
+                    }
+                    try {
+                        checkDowngrade(dataOwnerPkg, pkgLite);
+                    } catch (PackageManagerException e) {
+                        String errorMsg = "System app: " + packageName + " cannot be downgraded to"
+                                + " older than its preloaded version on the system image. "
+                                + e.getMessage();
+                        Slog.w(TAG, errorMsg);
+                        return PackageManager.INSTALL_FAILED_VERSION_DOWNGRADE;
+                    }
                 }
             }
         }