RE: [patch] fix uninitialized variable in dynamic linker

[Matthew Fortune <Matthew dot Fortune at imgtec dot com>]

Sandra Loosemore <sandra@codesourcery.com> writes:
> When we were testing glibc 2.21 here, we were getting some mysterious
> dynamic linking failures on MIPS due to the recent-ish changes for that
> target to ignore objects with incompatible FP ABIs.  On further

Thanks for looking at this, sorry to not find it during my testing of
the fpabi work.

> investigation, it turned out that the dynamic linker's own entry in the
> link map had an invalid l_mach.fpabi value.  I tracked this down to
> failure to initialize that field in the stack-allocated bootstrap_map
> structure in _dl_start; _dl_start_final was then happily copying the
> uninitialized l_mach value into the real map data structure.

I'm quite confused as to why I never saw this during test, I had over
70000 tests run correctly and I'd have thought I would see this at least
once.

> The attached patch zero-initializes the entire bootstrap_map data
> structure.  I thought this was better than selectively initializing
> specific fields since it future-proofs the code against similar errors
> involving other fields that might be added (or used) in the future.

This sounds good.

> I've verified that this fixes the 2.21 MIPS problems we saw.  Is this
> patch OK for mainline head, or is further testing required?

I can't say OK as I don't understand this area of the code well enough
but can at least confirm that the code I added relies on the fpabi
field being zero initialised which looked like it held true.

Thanks,
Matthew