Force WebDatabase version to max(version, compatible version) before migration.

chrome/browser/webdata/web_database.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome/browser/webdata/web_database.h"
 
 #include <algorithm>
 
 #include "chrome/browser/diagnostics/sqlite_diagnostics.h"
 #include "chrome/browser/webdata/autofill_table.h"
@@ skipping 140 matching lines @@
   // If the migration fails we return an error to caller and do not commit
   // the migration.
   sql::InitStatus migration_status = MigrateOldVersionsAsNeeded();
   if (migration_status != sql::INIT_OK)
     return migration_status;
 
   return transaction.Commit() ? sql::INIT_OK : sql::INIT_FAILURE;
 }
 
 sql::InitStatus WebDatabase::MigrateOldVersionsAsNeeded() {
+  // Some malware tries to force protector to re-sign things by lowering the
+  // version number, causing migration to fail. Ensure the version number is at
+  // least as high as the compatible version number.
+  int current_version = std::max(meta_table_.GetVersionNumber(),
+                                 meta_table_.GetCompatibleVersionNumber());
+  if (current_version < meta_table_.GetCompatibleVersionNumber())

[dhollowa, 2012/07/09 20:26:06]

Shouldn't this be:
  if (meta_table_.GetVersionNumber() < meta_table_.GetCompatibleVersionNumber())
...

[Ivan Korotkov, 2012/07/09 20:51:04]

Ouch, you must be right. The test passed because there was a migration to verson
46 which still incremented the version field.

[Peter Kasting, 2012/07/09 21:22:01]

I'm sorry for suggesting this incorrect code to Ivan in the first place!

Ivan, you have LGTM in advance from me to fix/land/merge this.  (Feel free to
TBR.)

+    ChangeVersion(&meta_table_, current_version, false);
+
   // Migrate if necessary.
-  int current_version = meta_table_.GetVersionNumber();
   switch (current_version) {
     // Versions 1 - 19 are unhandled.  Version numbers greater than
     // kCurrentVersionNumber should have already been weeded out by the caller.
     default:
       // When the version is too old, we return failure error code.  The schema
       // is too out of date to migrate.
       // There should not be a released product that makes a database too old to
       // migrate. If we do encounter such a legacy database, we will need a
       // better solution to handle it (i.e., pop up a dialog to tell the user,
       // erase all their prefs and start over, etc.).
@@ skipping 165 matching lines @@
 
     // Add successive versions here.  Each should set the version number and
     // compatible version number as appropriate, then fall through to the next
     // case.
 
     case kCurrentVersionNumber:
       // No migration needed.
       return sql::INIT_OK;
   }
 }