[PATCH] vfprintf: validate nargs and maybe allocate from heap

[Ryan S. Arnold]

On Tue, Feb 14, 2012 at 4:30 PM, Kees Cook <kees@outflux.net> wrote:
> On Tue, Feb 14, 2012 at 04:20:17PM -0600, Ryan S. Arnold wrote:
>> Currently I'm testing PowerPC 64-bit and bug-vfprintf-nargs is getting
>> killed by the skeleton code due to a timeout before the expected
>> SEGV happens.
>
> Hrm, I wonder if this timeout is from it allocating giant memory region
> using a layout that actually allows it without crashing into other things.
> (i.e. x86_64 would always very rapidly crash, but I don't know about
> ppc's layout.)

I'm not terribly familiar with how large allocations are handled.
Eventually it DOES crash if given a large enough TIMEOUTFACTOR.

>> Of course, on a system that's not under loader this may SEGV before
>> the timeout is hit and SIGALRM is raised.
>
> Perhaps under 64-bit, it should just skip the test entirely? The 64-bit
> case is meaningless anyway.

If that's desired then you'd remove the assignment of the testcase to
'tests' in stdio-common/Makefile and put it here:

sysdeps/wordsize-32/Makefile:

ifeq ($(subdir),stdio-common)
tests += bug-vfprintf-nargs
endif

Perhaps someone else has an opinion on this?

Ryan S. Arnold