why Glibc does not build with clang?

[Jeff Law]

On 05/16/14 07:53, Ondřej Bílka wrote:
>>
> All you need is reliable way to get stack boundaries. I proposed to add
> these some time ago. It would make alloca failures reliable without
> need of gcc support.
>
> A better alternative than ten line boilerplate alloca with fallback to malloc
> would be using malloca, that handles these automatically. With stack
> bounds it could allocate fairly safely, without these it must resort to
> heuristic like size is less than 65536.
Better yet, stop using alloca.

Seriously.  I don't have hard data, but there's little doubt in my mind 
that if we were to look at CVEs for glibc, the majority are due to 
unbound allocas.

Experience clearly shows that we consistently get it wrong with alloca. 
  IMHO, it should simply be banned from glibc (and everywhere, but let's 
start small).

Yes, I know it's orders of magnitude faster than malloc.  Yes I know we 
get automagic cleanup.  But if using it consistently results in 
incorrect code that attackers can exploit, then the performance aspects 
really should take a back seat.

Just MHO.

Jeff