Re: [PATCH v2 0/8] Some object db protection when add_submodule_odb is used

> Nguyễn Thái Ngọc Duy <pclouds@gmail.com> writes:
>
>> The idea behind this series is, after add_submodule_odb, odb may have
>> new temporary objects that only appear after the call. These temporary
>> objects may lead to repo corruption (e.g. some new objects are created
>> and point to these temporary objects). This series attempts to catch
>> those cases. It would make it safer to dig deeper into submodule's odb,
>> e.g. to implement unified git-diff.
>>
>> Previous approach [1] is record the odb source, then check if the
>> source is from submodule's odb. But that means we rely on the
>> lookup order in sha1_file.c. This approach instead allows the caller
>> to select what odb sources it wants to look up from.
>>
>> The checks are also less drastic than before. Checks are now done at
>> higher level, e.g. commit_tree(), instead of at write_sha1_file,
>> because we do allow to write objects that point to nowhere.
>>
>> Another new thing from previous round is I completely forbid the use
>> of add_submodule_odb in security sensitive commands like index-pack or
>> rev-list. We could loosen up later if we need to.
>>
>> For fun, I set object_database_contaminated to 1 by default and ran
>> the test suite. It passed :)
>
> How does this interact with alternates set up by the user?  It's not
> immediately obvious from the commit messages (hint hint) or the comments
> near ODB_LOCAL etc.