Re: [PATCH 01/15] string_list: add string_list_duplicate

From: Junio C Hamano <gitster@pobox.com>
Date: Apr 27, 2016, 21:11 UTC
Message-ID: <xmqqzise7o4l.fsf@gitster.mtv.corp.google.com>
In-Reply-To: <CAGZ79kbWMN3YG5Jtz8i8Y9A3id8bX-YxSWp19+yGAdzMX_wKKA@mail.gmail.com>

Stefan Beller <sbeller@google.com> writes:

Show 8 quoted lines

> When not duplicating git_config_get_value_multi("submodule.defaultGroup");
> I run into
>
> Program received signal SIGSEGV, Segmentation fault.
> ...
> So the string list seems to be corrupted here.
> Someone stomping over our memory? How long is the result
> of git_config_get_value_multi deemed to be stable and usable?

That call goes to

    git_config_get_value_multi()
    -> git_configset_get_value_multi()
       -> configset_find_element()

the returned value from there would be either NULL or the list of values that belong to the config cache layer, i.e. a caller of the API can peek but is not allowed to modify it.

So if you are modifying the value you obtain from the API, you must make a copy; otherwise you will "stomp over" memory that belongs to the config cache layer, not to you.