[PATCHv3][PING] Enable -fsanitize-recover for KASan

Alexey Samsonov samsonov@google.com
Tue Sep 30 01:05:00 GMT 2014


On Mon, Sep 29, 2014 at 5:24 PM, Konstantin Serebryany
<konstantin.s.serebryany@gmail.com> wrote:
>
> On Mon, Sep 29, 2014 at 4:26 PM, Alexey Samsonov <samsonov@google.com> wrote:
> > On Mon, Sep 29, 2014 at 4:17 PM, Jakub Jelinek <jakub@redhat.com> wrote:
> >> On Mon, Sep 29, 2014 at 03:36:20PM -0700, Alexey Samsonov wrote:
> >>> -fasan-recover doesn't look like a good idea - for instance, in Clang, we
> >>> never use "?san"
> >>> in flag names, preferring -fsanitize-whatever. What's the rationale behind
> >>> splitting
> >>> -fsanitize-recover in two flags (ASan- and UBSan- specific)?
> >>> Is there no way to keep a single -f(no-)sanitize-recover for that purpose?
> >>> Now it works
> >>> only for UBSan checks, but we may extend it to another sanitizers as well.
> >>
> >> The problem is that if we start using it for ASan, it needs to have a
> >> different default, because ASan wants to abort by default, while UBSan
> >> recover by default.  -fsanitize=kernel-address w (KASan) wants to recover
> >> by default.  So, the option is either to never support recover for
> >> -fsanitize=address, for ubsan keep -fsanitize-recover (by default) as is
> >> and for kasan use that same switch, or have separate flags.
> >>
> >>         Jakub
> >
> > I don't think we ever going to support recovery for regular ASan
> > (Kostya, correct me if I'm wrong).
>
> I hope so too.
> Another point is that with asan-instrumentation-with-call-threshold=0
> (instrumentation with callbacks)
> we can and probably will allow to recover from errors (glibc demands that),
> but that does not require any compile-time flag.


So, if we switch to instrumentation to callbacks (which are not
necessarily noreturn),
-fsanitize-recover is the thing we plan to support?

>
>
>
> > I see no problem in enabling -fsanitize-recover by default for
> > -fsanitize=undefined and
>
> This becomes more interesting when we use asan and ubsan together.
> Which default setting is stronger? :)

We can preserve the default behavior for each tool (no recovery for
ASan, recovery for UBSan)
unless recovery mode is explicitly specified.

>
> > -fsanitize=kernel-address. We can, potentially, extend
> > -fsanitize-recover flag to take the same values as -fsanitize= one,
> > so that one can specify which sanitizers are recoverable, and which
> > are not, but I'd try to make this a last resort - this is too complex.
> >
> > --
> > Alexey Samsonov, Mountain View, CA




-- 
Alexey Samsonov, Mountain View, CA



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