linux-kernel - Re: [PATCH v9 3/4] kasan: Add report for async mode

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Date:   Fri, 29 Jan 2021 18:56:07 +0100
From:   Andrey Konovalov <andreyknvl@...gle.com>
To:     Vincenzo Frascino <vincenzo.frascino@....com>
Cc:     Linux ARM <linux-arm-kernel@...ts.infradead.org>,
        LKML <linux-kernel@...r.kernel.org>,
        kasan-dev <kasan-dev@...glegroups.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will@...nel.org>,
        Dmitry Vyukov <dvyukov@...gle.com>,
        Andrey Ryabinin <aryabinin@...tuozzo.com>,
        Alexander Potapenko <glider@...gle.com>,
        Marco Elver <elver@...gle.com>,
        Evgenii Stepanov <eugenis@...gle.com>,
        Branislav Rankov <Branislav.Rankov@....com>
Subject: Re: [PATCH v9 3/4] kasan: Add report for async mode

On Fri, Jan 29, 2021 at 6:44 PM Vincenzo Frascino
<vincenzo.frascino@....com> wrote:
>
>
>
> On 1/29/21 5:40 PM, Andrey Konovalov wrote:
> > On Tue, Jan 26, 2021 at 2:46 PM Vincenzo Frascino
> > <vincenzo.frascino@....com> wrote:
> >>
> >> KASAN provides an asynchronous mode of execution.
> >>
> >> Add reporting functionality for this mode.
> >>
> >> Cc: Dmitry Vyukov <dvyukov@...gle.com>
> >> Cc: Andrey Ryabinin <aryabinin@...tuozzo.com>
> >> Cc: Alexander Potapenko <glider@...gle.com>
> >> Cc: Andrey Konovalov <andreyknvl@...gle.com>
> >> Reviewed-by: Andrey Konovalov <andreyknvl@...gle.com>
> >> Signed-off-by: Vincenzo Frascino <vincenzo.frascino@....com>
> >> ---
> >>  include/linux/kasan.h |  6 ++++++
> >>  mm/kasan/report.c     | 13 +++++++++++++
> >>  2 files changed, 19 insertions(+)
> >>
> >> diff --git a/include/linux/kasan.h b/include/linux/kasan.h
> >> index bb862d1f0e15..b6c502dad54d 100644
> >> --- a/include/linux/kasan.h
> >> +++ b/include/linux/kasan.h
> >> @@ -360,6 +360,12 @@ static inline void *kasan_reset_tag(const void *addr)
> >>
> >>  #endif /* CONFIG_KASAN_SW_TAGS || CONFIG_KASAN_HW_TAGS*/
> >>
> >> +#ifdef CONFIG_KASAN_HW_TAGS
> >> +
> >> +void kasan_report_async(void);
> >> +
> >> +#endif /* CONFIG_KASAN_HW_TAGS */
> >> +
> >>  #ifdef CONFIG_KASAN_SW_TAGS
> >>  void __init kasan_init_sw_tags(void);
> >>  #else
> >> diff --git a/mm/kasan/report.c b/mm/kasan/report.c
> >> index 87b271206163..69bad9c01aed 100644
> >> --- a/mm/kasan/report.c
> >> +++ b/mm/kasan/report.c
> >> @@ -360,6 +360,19 @@ void kasan_report_invalid_free(void *object, unsigned long ip)
> >>         end_report(&flags, (unsigned long)object);
> >>  }
> >>
> >> +#ifdef CONFIG_KASAN_HW_TAGS
> >> +void kasan_report_async(void)
> >> +{
> >> +       unsigned long flags;
> >> +
> >> +       start_report(&flags);
> >> +       pr_err("BUG: KASAN: invalid-access\n");
> >> +       pr_err("Asynchronous mode enabled: no access details available\n");

Could you also add an empty line here before the stack trace while at it?

> >> +       dump_stack();
> >> +       end_report(&flags);
> >
> > This conflicts with "kasan: use error_report_end tracepoint" that's in mm.
> >
> > I suggest to call end_report(&flags, 0) here and check addr !=0 in
> > end_report() before calling trace_error_report_end().
> >
>
> I just noticed and about to post a rebased version with end_report(&flags, 0).
>
>
> >> +}
> >> +#endif /* CONFIG_KASAN_HW_TAGS */
> >> +
> >>  static void __kasan_report(unsigned long addr, size_t size, bool is_write,
> >>                                 unsigned long ip)
> >>  {
> >> --
> >> 2.30.0
> >>
>
> --
> Regards,
> Vincenzo