[PATCH] vfprintf: validate nargs and positional offsets

[Joseph S. Myers]

On Fri, 3 Feb 2012, Kees Cook wrote:

> - Hybrid: use calloc/malloc when more than a page worth of memory would
> be needed, otherwise just stick with alloca. This would mean that only
> format strings with more than 204 (on 32-bit, or 102 on 64-bit) would
> need to hit the heap.

__libc_use_alloca is the standard test for doing this sort of thing; it 
should be used in any case where an alloca allocation might otherwise have 
unbounded size but you don't want to use malloc unconditionally, unless 
there is a good reason to do otherwise.

-- 
Joseph S. Myers
joseph@codesourcery.com