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Re: [PATCHv3][PING] Enable -fsanitize-recover for KASan
- From: Konstantin Serebryany <konstantin dot s dot serebryany at gmail dot com>
- To: Alexey Samsonov <samsonov at google dot com>
- Cc: Jakub Jelinek <jakub at redhat dot com>, Yury Gribov <y dot gribov at samsung dot com>, GCC Patches <gcc-patches at gcc dot gnu dot org>, Dmitry Vyukov <dvyukov at google dot com>, Andrey Ryabinin <a dot ryabinin at samsung dot com>, Konstantin Khlebnikov <k dot khlebnikov at samsung dot com>
- Date: Mon, 29 Sep 2014 17:24:02 -0700
- Subject: Re: [PATCHv3][PING] Enable -fsanitize-recover for KASan
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- References: <54095E23 dot 6050900 at samsung dot com> <5416B3A2 dot 4050200 at samsung dot com> <54299507 dot 7090800 at samsung dot com> <20140929174357 dot GH17454 at tucnak dot redhat dot com> <CAGQ9bdzcCO6CfQ7nG+xeAh63fs-GASiTExTvZfjJtMA67_4feQ at mail dot gmail dot com> <CAGSYnCPwbgZ++2Jt2vE6-ytveSJwSQPZT5umLeKPVWsVjWzwPQ at mail dot gmail dot com> <20140929231720 dot GI17454 at tucnak dot redhat dot com> <CAGSYnCPAN83v+JOyw-jMLUEE2YjaNQykdTCG4rdd=o_ieC4vFA at mail dot gmail dot com>
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.
> 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? :)
> -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