Re: [PATCH, RFC] Introduce -fsanitize=use-after-scope

[Jakub Jelinek <jakub@redhat.com>]

On Fri, May 06, 2016 at 02:48:30PM +0300, Yury Gribov wrote:
> >6) As the use-after-scope stuff is already included in libsanitizer, no change is needed for the library
> 
> Note that upstream seems to use a different cmdline interface. They don't
> have a dedicated -fsanitize=use-after-scope and instead consider it to be a
> part of -fsanitize=address (disabled by default, enabled via -mllvm
> -asan-use-after-scope=1). I'd suggest to keep this interface (or at least
> discuss with them) and use GCC's --param.

I personally think -fsanitize=use-after-scope (which implies address
sanitization in it) is better, can upstream be convinved not to change it?

> FTR here's the upstream work on this: http://reviews.llvm.org/D19347
> 
> >Example:
> >
> >int
> >main (void)
> >{
> >   char *ptr;
> >   {
> >     char my_char[9];
> >     ptr = &my_char[0];
> >   }
> >
> >   *(ptr+9) = 'c';
> >}

Well, this testcase shows not just use after scope, but also out of bound
access.  Would be better not to combine it, at least in the majority of
testcases.

	Jakub