[patch v1] malloc: add malloc_zero_aborts tunable

[DJ Delorie]

Florian Weimer <fweimer@redhat.com> writes:
> We should really be using IFUNCs to select the entry points to the
> malloc code.

So this is turning out to be much more complex than anticipated.  After
a day of coding, mostly debugging, and many long conversations with an
AI about what was happening, it boils down to this:

* The malloc API's resolvers run VERY early in libc.so's loading

* ld.so's tunable_get_val() is not yet linked and crashes if you try to
  call it.

* __tunable_list[] is not available to libc.so

* there's nothing relevent in rtld_global[]

* _environ[] is also not initialized at this point

* there doesn't seem to be a way to get anything user-related to the
  resolver at that early stage in libc loading

* Even AIs start to hallucinate when dealing with glibc's internals ;-)


Suggestions?