* Re: [PATCH v6 2/2] kasan: Add memzero int for unaligned size at DEBUG
2021-07-05 10:32 ` [PATCH v6 2/2] kasan: Add memzero int for unaligned size at DEBUG yee.lee
@ 2021-07-05 10:45 ` Marco Elver
2021-07-05 11:12 ` Andrey Konovalov
2021-07-05 11:23 ` Andrey Konovalov
2 siblings, 0 replies; 9+ messages in thread
From: Marco Elver @ 2021-07-05 10:45 UTC (permalink / raw)
To: yee.lee
Cc: linux-kernel, nicholas.tang, Kuan-Ying.Lee, chinwen.chang,
Andrey Ryabinin, Alexander Potapenko, Dmitry Vyukov,
Andrew Morton, Andrey Konovalov, Matthias Brugger,
open list:KASAN, open list:MEMORY MANAGEMENT,
moderated list:ARM/Mediatek SoC support,
moderated list:ARM/Mediatek SoC support
On Mon, 5 Jul 2021 at 12:33, <yee.lee@mediatek.com> wrote:
> From: Yee Lee <yee.lee@mediatek.com>
>
> Issue: when SLUB debug is on, hwtag kasan_unpoison() would overwrite
> the redzone of object with unaligned size.
>
> An additional memzero_explicit() path is added to replacing init by
> hwtag instruction for those unaligned size at SLUB debug mode.
>
> The penalty is acceptable since they are only enabled in debug mode,
> not production builds. A block of comment is added for explanation.
>
> Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
> Cc: Alexander Potapenko <glider@google.com>
> Cc: Dmitry Vyukov <dvyukov@google.com>
> Cc: Andrew Morton <akpm@linux-foundation.org>
> Suggested-by: Marco Elver <elver@google.com>
> Suggested-by: Andrey Konovalov <andreyknvl@gmail.com>
> Signed-off-by: Yee Lee <yee.lee@mediatek.com>
Reviewed-by: Marco Elver <elver@google.com>
Thank you!
> ---
> mm/kasan/kasan.h | 12 ++++++++++++
> 1 file changed, 12 insertions(+)
>
> diff --git a/mm/kasan/kasan.h b/mm/kasan/kasan.h
> index 98e3059bfea4..d739cdd1621a 100644
> --- a/mm/kasan/kasan.h
> +++ b/mm/kasan/kasan.h
> @@ -9,6 +9,7 @@
> #ifdef CONFIG_KASAN_HW_TAGS
>
> #include <linux/static_key.h>
> +#include "../slab.h"
>
> DECLARE_STATIC_KEY_FALSE(kasan_flag_stacktrace);
> extern bool kasan_flag_async __ro_after_init;
> @@ -387,6 +388,17 @@ static inline void kasan_unpoison(const void *addr, size_t size, bool init)
>
> if (WARN_ON((unsigned long)addr & KASAN_GRANULE_MASK))
> return;
> + /*
> + * Explicitly initialize the memory with the precise object size to
> + * avoid overwriting the SLAB redzone. This disables initialization in
> + * the arch code and may thus lead to performance penalty. The penalty
> + * is accepted since SLAB redzones aren't enabled in production builds.
> + */
> + if (__slub_debug_enabled() &&
> + init && ((unsigned long)size & KASAN_GRANULE_MASK)) {
> + init = false;
> + memzero_explicit((void *)addr, size);
> + }
> size = round_up(size, KASAN_GRANULE_SIZE);
>
> hw_set_mem_tag_range((void *)addr, size, tag, init);
> --
> 2.18.0
^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [PATCH v6 2/2] kasan: Add memzero int for unaligned size at DEBUG
2021-07-05 10:32 ` [PATCH v6 2/2] kasan: Add memzero int for unaligned size at DEBUG yee.lee
2021-07-05 10:45 ` Marco Elver
@ 2021-07-05 11:12 ` Andrey Konovalov
2021-07-05 11:18 ` Marco Elver
2021-07-05 11:23 ` Andrey Konovalov
2 siblings, 1 reply; 9+ messages in thread
From: Andrey Konovalov @ 2021-07-05 11:12 UTC (permalink / raw)
To: yee.lee
Cc: LKML, nicholas.Tang, Kuan-Ying Lee, chinwen.chang,
Andrey Ryabinin, Alexander Potapenko, Dmitry Vyukov,
Andrew Morton, Matthias Brugger, open list:KASAN,
open list:MEMORY MANAGEMENT,
moderated list:ARM/Mediatek SoC support,
moderated list:ARM/Mediatek SoC support
On Mon, Jul 5, 2021 at 12:33 PM <yee.lee@mediatek.com> wrote:
>
> From: Yee Lee <yee.lee@mediatek.com>
>
> Issue: when SLUB debug is on, hwtag kasan_unpoison() would overwrite
> the redzone of object with unaligned size.
>
> An additional memzero_explicit() path is added to replacing init by
> hwtag instruction for those unaligned size at SLUB debug mode.
>
> The penalty is acceptable since they are only enabled in debug mode,
> not production builds. A block of comment is added for explanation.
>
> Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
> Cc: Alexander Potapenko <glider@google.com>
> Cc: Dmitry Vyukov <dvyukov@google.com>
> Cc: Andrew Morton <akpm@linux-foundation.org>
> Suggested-by: Marco Elver <elver@google.com>
> Suggested-by: Andrey Konovalov <andreyknvl@gmail.com>
> Signed-off-by: Yee Lee <yee.lee@mediatek.com>
> ---
> mm/kasan/kasan.h | 12 ++++++++++++
> 1 file changed, 12 insertions(+)
>
> diff --git a/mm/kasan/kasan.h b/mm/kasan/kasan.h
> index 98e3059bfea4..d739cdd1621a 100644
> --- a/mm/kasan/kasan.h
> +++ b/mm/kasan/kasan.h
> @@ -9,6 +9,7 @@
> #ifdef CONFIG_KASAN_HW_TAGS
>
> #include <linux/static_key.h>
> +#include "../slab.h"
>
> DECLARE_STATIC_KEY_FALSE(kasan_flag_stacktrace);
> extern bool kasan_flag_async __ro_after_init;
> @@ -387,6 +388,17 @@ static inline void kasan_unpoison(const void *addr, size_t size, bool init)
>
> if (WARN_ON((unsigned long)addr & KASAN_GRANULE_MASK))
> return;
> + /*
> + * Explicitly initialize the memory with the precise object size to
> + * avoid overwriting the SLAB redzone. This disables initialization in
> + * the arch code and may thus lead to performance penalty. The penalty
> + * is accepted since SLAB redzones aren't enabled in production builds.
> + */
> + if (__slub_debug_enabled() &&
What happened to slub_debug_enabled_unlikely()? Was it renamed? Why? I
didn't receive patch #1 of v6 (nor of v5).
> + init && ((unsigned long)size & KASAN_GRANULE_MASK)) {
> + init = false;
> + memzero_explicit((void *)addr, size);
> + }
> size = round_up(size, KASAN_GRANULE_SIZE);
>
> hw_set_mem_tag_range((void *)addr, size, tag, init);
> --
> 2.18.0
>
^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [PATCH v6 2/2] kasan: Add memzero int for unaligned size at DEBUG
2021-07-05 11:12 ` Andrey Konovalov
@ 2021-07-05 11:18 ` Marco Elver
2021-07-05 11:23 ` Andrey Konovalov
0 siblings, 1 reply; 9+ messages in thread
From: Marco Elver @ 2021-07-05 11:18 UTC (permalink / raw)
To: Andrey Konovalov
Cc: yee.lee, LKML, nicholas.tang, Kuan-Ying Lee, chinwen.chang,
Andrey Ryabinin, Alexander Potapenko, Dmitry Vyukov,
Andrew Morton, Matthias Brugger, open list:KASAN,
open list:MEMORY MANAGEMENT,
moderated list:ARM/Mediatek SoC support,
moderated list:ARM/Mediatek SoC support
On Mon, 5 Jul 2021 at 13:12, Andrey Konovalov <andreyknvl@gmail.com> wrote:
[...]
> > + /*
> > + * Explicitly initialize the memory with the precise object size to
> > + * avoid overwriting the SLAB redzone. This disables initialization in
> > + * the arch code and may thus lead to performance penalty. The penalty
> > + * is accepted since SLAB redzones aren't enabled in production builds.
> > + */
> > + if (__slub_debug_enabled() &&
>
> What happened to slub_debug_enabled_unlikely()? Was it renamed? Why? I
> didn't receive patch #1 of v6 (nor of v5).
Somebody had the same idea with the helper:
https://lkml.kernel.org/r/YOKsC75kJfCZwySD@elver.google.com
and Matthew didn't like the _unlikely() prefix.
Which meant we should just move the existing helper introduced in the
merge window.
Patch 1/2: https://lkml.kernel.org/r/20210705103229.8505-2-yee.lee@mediatek.com
Thanks,
-- Marco
^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [PATCH v6 2/2] kasan: Add memzero int for unaligned size at DEBUG
2021-07-05 11:18 ` Marco Elver
@ 2021-07-05 11:23 ` Andrey Konovalov
2021-07-05 13:53 ` Yee Lee
0 siblings, 1 reply; 9+ messages in thread
From: Andrey Konovalov @ 2021-07-05 11:23 UTC (permalink / raw)
To: Marco Elver
Cc: yee.lee, LKML, nicholas.tang, Kuan-Ying Lee, chinwen.chang,
Andrey Ryabinin, Alexander Potapenko, Dmitry Vyukov,
Andrew Morton, Matthias Brugger, open list:KASAN,
open list:MEMORY MANAGEMENT,
moderated list:ARM/Mediatek SoC support,
moderated list:ARM/Mediatek SoC support
On Mon, Jul 5, 2021 at 1:18 PM Marco Elver <elver@google.com> wrote:
>
> On Mon, 5 Jul 2021 at 13:12, Andrey Konovalov <andreyknvl@gmail.com> wrote:
> [...]
> > > + /*
> > > + * Explicitly initialize the memory with the precise object size to
> > > + * avoid overwriting the SLAB redzone. This disables initialization in
> > > + * the arch code and may thus lead to performance penalty. The penalty
> > > + * is accepted since SLAB redzones aren't enabled in production builds.
> > > + */
> > > + if (__slub_debug_enabled() &&
> >
> > What happened to slub_debug_enabled_unlikely()? Was it renamed? Why? I
> > didn't receive patch #1 of v6 (nor of v5).
>
> Somebody had the same idea with the helper:
> https://lkml.kernel.org/r/YOKsC75kJfCZwySD@elver.google.com
> and Matthew didn't like the _unlikely() prefix.
>
> Which meant we should just move the existing helper introduced in the
> merge window.
>
> Patch 1/2: https://lkml.kernel.org/r/20210705103229.8505-2-yee.lee@mediatek.com
Got it. Thank you, Marco!
^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [PATCH v6 2/2] kasan: Add memzero int for unaligned size at DEBUG
2021-07-05 11:23 ` Andrey Konovalov
@ 2021-07-05 13:53 ` Yee Lee
0 siblings, 0 replies; 9+ messages in thread
From: Yee Lee @ 2021-07-05 13:53 UTC (permalink / raw)
To: Andrey Konovalov, Marco Elver, Andrew Morton
Cc: LKML, nicholas.tang, Kuan-Ying Lee, chinwen.chang,
Andrey Ryabinin, Alexander Potapenko, Dmitry Vyukov,
Andrew Morton, Matthias Brugger, open list:KASAN,
open list:MEMORY MANAGEMENT,
moderated list:ARM/Mediatek SoC support,
moderated list:ARM/Mediatek SoC support
Thank you, Macro. I thought members in "suggested-by" would be put in
the list as well... And thank you guys for the review these days.
@Andrew Motom
Hi Andrew,
Could you help to push the patches? We are dealing with the issue and
would backport to Android porject right after the action.
Appreciated!
BR,
Yee
On Mon, 2021-07-05 at 13:23 +0200, Andrey Konovalov wrote:
> On Mon, Jul 5, 2021 at 1:18 PM Marco Elver <elver@google.com> wrote:
> >
> > On Mon, 5 Jul 2021 at 13:12, Andrey Konovalov <andreyknvl@gmail.com
> > > wrote:
> > [...]
> > > > + /*
> > > > + * Explicitly initialize the memory with the precise
> > > > object size to
> > > > + * avoid overwriting the SLAB redzone. This disables
> > > > initialization in
> > > > + * the arch code and may thus lead to performance
> > > > penalty. The penalty
> > > > + * is accepted since SLAB redzones aren't enabled in
> > > > production builds.
> > > > + */
> > > > + if (__slub_debug_enabled() &&
> > >
> > > What happened to slub_debug_enabled_unlikely()? Was it renamed?
> > > Why? I
> > > didn't receive patch #1 of v6 (nor of v5).
> >
> > Somebody had the same idea with the helper:
> > https://lkml.kernel.org/r/YOKsC75kJfCZwySD@elver.google.com
> > and Matthew didn't like the _unlikely() prefix.
> >
> > Which meant we should just move the existing helper introduced in
> > the
> > merge window.
> >
> > Patch 1/2:
> > https://lkml.kernel.org/r/20210705103229.8505-2-yee.lee@mediatek.com
>
> Got it. Thank you, Marco!
^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [PATCH v6 2/2] kasan: Add memzero int for unaligned size at DEBUG
2021-07-05 10:32 ` [PATCH v6 2/2] kasan: Add memzero int for unaligned size at DEBUG yee.lee
2021-07-05 10:45 ` Marco Elver
2021-07-05 11:12 ` Andrey Konovalov
@ 2021-07-05 11:23 ` Andrey Konovalov
2 siblings, 0 replies; 9+ messages in thread
From: Andrey Konovalov @ 2021-07-05 11:23 UTC (permalink / raw)
To: yee.lee
Cc: LKML, nicholas.Tang, Kuan-Ying Lee, chinwen.chang,
Andrey Ryabinin, Alexander Potapenko, Dmitry Vyukov,
Andrew Morton, Matthias Brugger, open list:KASAN,
open list:MEMORY MANAGEMENT,
moderated list:ARM/Mediatek SoC support,
moderated list:ARM/Mediatek SoC support
On Mon, Jul 5, 2021 at 12:33 PM <yee.lee@mediatek.com> wrote:
>
> From: Yee Lee <yee.lee@mediatek.com>
>
> Issue: when SLUB debug is on, hwtag kasan_unpoison() would overwrite
> the redzone of object with unaligned size.
>
> An additional memzero_explicit() path is added to replacing init by
> hwtag instruction for those unaligned size at SLUB debug mode.
>
> The penalty is acceptable since they are only enabled in debug mode,
> not production builds. A block of comment is added for explanation.
>
> Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
> Cc: Alexander Potapenko <glider@google.com>
> Cc: Dmitry Vyukov <dvyukov@google.com>
> Cc: Andrew Morton <akpm@linux-foundation.org>
> Suggested-by: Marco Elver <elver@google.com>
> Suggested-by: Andrey Konovalov <andreyknvl@gmail.com>
> Signed-off-by: Yee Lee <yee.lee@mediatek.com>
> ---
> mm/kasan/kasan.h | 12 ++++++++++++
> 1 file changed, 12 insertions(+)
>
> diff --git a/mm/kasan/kasan.h b/mm/kasan/kasan.h
> index 98e3059bfea4..d739cdd1621a 100644
> --- a/mm/kasan/kasan.h
> +++ b/mm/kasan/kasan.h
> @@ -9,6 +9,7 @@
> #ifdef CONFIG_KASAN_HW_TAGS
>
> #include <linux/static_key.h>
> +#include "../slab.h"
>
> DECLARE_STATIC_KEY_FALSE(kasan_flag_stacktrace);
> extern bool kasan_flag_async __ro_after_init;
> @@ -387,6 +388,17 @@ static inline void kasan_unpoison(const void *addr, size_t size, bool init)
>
> if (WARN_ON((unsigned long)addr & KASAN_GRANULE_MASK))
> return;
> + /*
> + * Explicitly initialize the memory with the precise object size to
> + * avoid overwriting the SLAB redzone. This disables initialization in
> + * the arch code and may thus lead to performance penalty. The penalty
> + * is accepted since SLAB redzones aren't enabled in production builds.
> + */
> + if (__slub_debug_enabled() &&
> + init && ((unsigned long)size & KASAN_GRANULE_MASK)) {
> + init = false;
> + memzero_explicit((void *)addr, size);
> + }
> size = round_up(size, KASAN_GRANULE_SIZE);
>
> hw_set_mem_tag_range((void *)addr, size, tag, init);
> --
> 2.18.0
>
Reviewed-by: Andrey Konovalov <andreyknvl@gmail.com>
^ permalink raw reply [flat|nested] 9+ messages in thread