linux-kernel - Re: [PATCH v2 2/2] kasan, arm64: fix pointer tags in KASAN reports

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Message-ID: <CAAeHK+w49og7TTfwA3MdySkXsc0ndNYDNTO2o2YTo=kqb7U3Fw@mail.gmail.com>
Date:   Fri, 15 Jan 2021 13:48:38 +0100
From:   Andrey Konovalov <andreyknvl@...gle.com>
To:     Catalin Marinas <catalin.marinas@....com>
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        Vincenzo Frascino <vincenzo.frascino@....com>,
        Dmitry Vyukov <dvyukov@...gle.com>,
        Alexander Potapenko <glider@...gle.com>,
        Marco Elver <elver@...gle.com>,
        Will Deacon <will.deacon@....com>,
        Andrey Ryabinin <aryabinin@...tuozzo.com>,
        Peter Collingbourne <pcc@...gle.com>,
        Evgenii Stepanov <eugenis@...gle.com>,
        Branislav Rankov <Branislav.Rankov@....com>,
        Kevin Brodsky <kevin.brodsky@....com>,
        kasan-dev <kasan-dev@...glegroups.com>,
        Linux ARM <linux-arm-kernel@...ts.infradead.org>,
        Linux Memory Management List <linux-mm@...ck.org>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2 2/2] kasan, arm64: fix pointer tags in KASAN reports

On Fri, Jan 15, 2021 at 11:49 AM Catalin Marinas
<catalin.marinas@....com> wrote:
>
> On Thu, Jan 14, 2021 at 08:33:57PM +0100, Andrey Konovalov wrote:
> > As of the "arm64: expose FAR_EL1 tag bits in siginfo" patch, the address
> > that is passed to report_tag_fault has pointer tags in the format of 0x0X,
> > while KASAN uses 0xFX format (note the difference in the top 4 bits).
> >
> > Fix up the pointer tag before calling kasan_report.
> >
> > Link: https://linux-review.googlesource.com/id/I9ced973866036d8679e8f4ae325de547eb969649
> > Fixes: dceec3ff7807 ("arm64: expose FAR_EL1 tag bits in siginfo")
> > Fixes: 4291e9ee6189 ("kasan, arm64: print report from tag fault handler")
> > Signed-off-by: Andrey Konovalov <andreyknvl@...gle.com>
> > ---
> >  arch/arm64/mm/fault.c | 2 ++
> >  1 file changed, 2 insertions(+)
> >
> > diff --git a/arch/arm64/mm/fault.c b/arch/arm64/mm/fault.c
> > index 3c40da479899..a218f6f2fdc8 100644
> > --- a/arch/arm64/mm/fault.c
> > +++ b/arch/arm64/mm/fault.c
> > @@ -304,6 +304,8 @@ static void report_tag_fault(unsigned long addr, unsigned int esr,
> >  {
> >       bool is_write  = ((esr & ESR_ELx_WNR) >> ESR_ELx_WNR_SHIFT) != 0;
> >
> > +     /* The format of KASAN tags is 0xF<x>. */
> > +     addr |= (0xF0UL << MTE_TAG_SHIFT);
> >       /*
> >        * SAS bits aren't set for all faults reported in EL1, so we can't
> >        * find out access size.
>
> I already replied here but I don't see any change in v2:
>
> https://lore.kernel.org/linux-arm-kernel/20210113165441.GC27045@gaia/

Hi Catalin,

Sorry, Gmail decided to mark all your emails as spam for some reason,
so I didn't see any of them :(

I'll fix this in v3.

Thanks!