diff mbox series

[v9,21/44] kasan: kasan_non_canonical_hook only for software modes

Message ID 49f7f2c12b0d5805f9a7b7092b986bbc2dd077a1.1605046192.git.andreyknvl@google.com (mailing list archive)
State New, archived
Headers show
Series [v9,01/44] kasan: drop unnecessary GPL text from comment headers | expand

Commit Message

Andrey Konovalov Nov. 10, 2020, 10:10 p.m. UTC 
This is a preparatory commit for the upcoming addition of a new hardware
tag-based (MTE-based) KASAN mode.

kasan_non_canonical_hook() is only applicable to KASAN modes that use
shadow memory, and won't be needed for hardware tag-based KASAN.

No functional changes for software modes.

Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
Signed-off-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
Reviewed-by: Marco Elver <elver@google.com>
---
Change-Id: Icc9f5ef100a2e86f3a4214a0c3131a68266181b2
---
 mm/kasan/report.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

Comments

Alexander Potapenko Nov. 11, 2020, 3:08 p.m. UTC | #1 
On Tue, Nov 10, 2020 at 11:11 PM Andrey Konovalov <andreyknvl@google.com> wrote:
>
> This is a preparatory commit for the upcoming addition of a new hardware
> tag-based (MTE-based) KASAN mode.
>
> kasan_non_canonical_hook() is only applicable to KASAN modes that use
> shadow memory, and won't be needed for hardware tag-based KASAN.
>
> No functional changes for software modes.
>
> Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
> Signed-off-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
> Reviewed-by: Marco Elver <elver@google.com>
> ---
> Change-Id: Icc9f5ef100a2e86f3a4214a0c3131a68266181b2
> ---
>  mm/kasan/report.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/mm/kasan/report.c b/mm/kasan/report.c
> index 5d5733831ad7..594bad2a3a5e 100644
> --- a/mm/kasan/report.c
> +++ b/mm/kasan/report.c
> @@ -403,7 +403,8 @@ bool kasan_report(unsigned long addr, size_t size, bool is_write,
>         return ret;
>  }
>
> -#ifdef CONFIG_KASAN_INLINE
> +#if (defined(CONFIG_KASAN_GENERIC) || defined(CONFIG_KASAN_SW_TAGS)) && \
> +       defined(CONFIG_KASAN_INLINE)
>  /*
>   * With CONFIG_KASAN_INLINE, accesses to bogus pointers (outside the high
>   * canonical half of the address space) cause out-of-bounds shadow memory reads

Perhaps this comment also needs to be updated.

> --
> 2.29.2.222.g5d2a92d10f8-goog
>
Andrey Konovalov Nov. 11, 2020, 6:52 p.m. UTC | #2 
On Wed, Nov 11, 2020 at 4:09 PM Alexander Potapenko <glider@google.com> wrote:
>
> On Tue, Nov 10, 2020 at 11:11 PM Andrey Konovalov <andreyknvl@google.com> wrote:
> >
> > This is a preparatory commit for the upcoming addition of a new hardware
> > tag-based (MTE-based) KASAN mode.
> >
> > kasan_non_canonical_hook() is only applicable to KASAN modes that use
> > shadow memory, and won't be needed for hardware tag-based KASAN.
> >
> > No functional changes for software modes.
> >
> > Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
> > Signed-off-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
> > Reviewed-by: Marco Elver <elver@google.com>
> > ---
> > Change-Id: Icc9f5ef100a2e86f3a4214a0c3131a68266181b2
> > ---
> >  mm/kasan/report.c | 3 ++-
> >  1 file changed, 2 insertions(+), 1 deletion(-)
> >
> > diff --git a/mm/kasan/report.c b/mm/kasan/report.c
> > index 5d5733831ad7..594bad2a3a5e 100644
> > --- a/mm/kasan/report.c
> > +++ b/mm/kasan/report.c
> > @@ -403,7 +403,8 @@ bool kasan_report(unsigned long addr, size_t size, bool is_write,
> >         return ret;
> >  }
> >
> > -#ifdef CONFIG_KASAN_INLINE
> > +#if (defined(CONFIG_KASAN_GENERIC) || defined(CONFIG_KASAN_SW_TAGS)) && \
> > +       defined(CONFIG_KASAN_INLINE)
> >  /*
> >   * With CONFIG_KASAN_INLINE, accesses to bogus pointers (outside the high
> >   * canonical half of the address space) cause out-of-bounds shadow memory reads
>
> Perhaps this comment also needs to be updated.

In what way?
Alexander Potapenko Nov. 12, 2020, 3:16 p.m. UTC | #3 
On Wed, Nov 11, 2020 at 7:52 PM 'Andrey Konovalov' via kasan-dev
<kasan-dev@googlegroups.com> wrote:
>
> On Wed, Nov 11, 2020 at 4:09 PM Alexander Potapenko <glider@google.com> wrote:
> >
> > On Tue, Nov 10, 2020 at 11:11 PM Andrey Konovalov <andreyknvl@google.com> wrote:
> > >
> > > This is a preparatory commit for the upcoming addition of a new hardware
> > > tag-based (MTE-based) KASAN mode.
> > >
> > > kasan_non_canonical_hook() is only applicable to KASAN modes that use
> > > shadow memory, and won't be needed for hardware tag-based KASAN.
> > >
> > > No functional changes for software modes.
> > >
> > > Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
> > > Signed-off-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
> > > Reviewed-by: Marco Elver <elver@google.com>
> > > ---
> > > Change-Id: Icc9f5ef100a2e86f3a4214a0c3131a68266181b2
> > > ---
> > >  mm/kasan/report.c | 3 ++-
> > >  1 file changed, 2 insertions(+), 1 deletion(-)
> > >
> > > diff --git a/mm/kasan/report.c b/mm/kasan/report.c
> > > index 5d5733831ad7..594bad2a3a5e 100644
> > > --- a/mm/kasan/report.c
> > > +++ b/mm/kasan/report.c
> > > @@ -403,7 +403,8 @@ bool kasan_report(unsigned long addr, size_t size, bool is_write,
> > >         return ret;
> > >  }
> > >
> > > -#ifdef CONFIG_KASAN_INLINE
> > > +#if (defined(CONFIG_KASAN_GENERIC) || defined(CONFIG_KASAN_SW_TAGS)) && \
> > > +       defined(CONFIG_KASAN_INLINE)
> > >  /*
> > >   * With CONFIG_KASAN_INLINE, accesses to bogus pointers (outside the high
> > >   * canonical half of the address space) cause out-of-bounds shadow memory reads
> >
> > Perhaps this comment also needs to be updated.
>
> In what way?

Ok, maybe not. I thought you were restricting the set of configs under
which this hook is used, so this should've been explained.
But as far as I understand, CONFIG_KASAN_INLINE already implies
"defined(CONFIG_KASAN_GENERIC) || defined(CONFIG_KASAN_SW_TAGS)",
doesn't it?
Maybe this change is not needed at all then?

>
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Andrey Konovalov Nov. 12, 2020, 7:27 p.m. UTC | #4 
On Thu, Nov 12, 2020 at 4:16 PM Alexander Potapenko <glider@google.com> wrote:
>
> On Wed, Nov 11, 2020 at 7:52 PM 'Andrey Konovalov' via kasan-dev
> <kasan-dev@googlegroups.com> wrote:
> >
> > On Wed, Nov 11, 2020 at 4:09 PM Alexander Potapenko <glider@google.com> wrote:
> > >
> > > On Tue, Nov 10, 2020 at 11:11 PM Andrey Konovalov <andreyknvl@google.com> wrote:
> > > >
> > > > This is a preparatory commit for the upcoming addition of a new hardware
> > > > tag-based (MTE-based) KASAN mode.
> > > >
> > > > kasan_non_canonical_hook() is only applicable to KASAN modes that use
> > > > shadow memory, and won't be needed for hardware tag-based KASAN.
> > > >
> > > > No functional changes for software modes.
> > > >
> > > > Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
> > > > Signed-off-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
> > > > Reviewed-by: Marco Elver <elver@google.com>
> > > > ---
> > > > Change-Id: Icc9f5ef100a2e86f3a4214a0c3131a68266181b2
> > > > ---
> > > >  mm/kasan/report.c | 3 ++-
> > > >  1 file changed, 2 insertions(+), 1 deletion(-)
> > > >
> > > > diff --git a/mm/kasan/report.c b/mm/kasan/report.c
> > > > index 5d5733831ad7..594bad2a3a5e 100644
> > > > --- a/mm/kasan/report.c
> > > > +++ b/mm/kasan/report.c
> > > > @@ -403,7 +403,8 @@ bool kasan_report(unsigned long addr, size_t size, bool is_write,
> > > >         return ret;
> > > >  }
> > > >
> > > > -#ifdef CONFIG_KASAN_INLINE
> > > > +#if (defined(CONFIG_KASAN_GENERIC) || defined(CONFIG_KASAN_SW_TAGS)) && \
> > > > +       defined(CONFIG_KASAN_INLINE)
> > > >  /*
> > > >   * With CONFIG_KASAN_INLINE, accesses to bogus pointers (outside the high
> > > >   * canonical half of the address space) cause out-of-bounds shadow memory reads
> > >
> > > Perhaps this comment also needs to be updated.
> >
> > In what way?
>
> Ok, maybe not. I thought you were restricting the set of configs under
> which this hook is used, so this should've been explained.
> But as far as I understand, CONFIG_KASAN_INLINE already implies
> "defined(CONFIG_KASAN_GENERIC) || defined(CONFIG_KASAN_SW_TAGS)",
> doesn't it?
> Maybe this change is not needed at all then?

Ah, yes, you're right. Will drop this patch, thanks!
diff mbox series

Patch

diff --git a/mm/kasan/report.c b/mm/kasan/report.c
index 5d5733831ad7..594bad2a3a5e 100644
--- a/mm/kasan/report.c
+++ b/mm/kasan/report.c
@@ -403,7 +403,8 @@  bool kasan_report(unsigned long addr, size_t size, bool is_write,
 	return ret;
 }
 
-#ifdef CONFIG_KASAN_INLINE
+#if (defined(CONFIG_KASAN_GENERIC) || defined(CONFIG_KASAN_SW_TAGS)) && \
+	defined(CONFIG_KASAN_INLINE)
 /*
  * With CONFIG_KASAN_INLINE, accesses to bogus pointers (outside the high
  * canonical half of the address space) cause out-of-bounds shadow memory reads