* [PATCH v2 0/1] kasan: fix redzone overwritten issue under SLUB debug
@ 2021-06-23 13:35 yee.lee
2021-06-23 13:35 ` [PATCH v2 1/1] kasan: Add memzero init for unaligned size " yee.lee
2021-06-23 13:51 ` [PATCH v2 0/1] kasan: fix redzone overwritten issue " Yee Lee
0 siblings, 2 replies; 8+ messages in thread
From: yee.lee @ 2021-06-23 13:35 UTC (permalink / raw)
To: andreyknvl
Cc: wsd_upstream, Yee Lee, Matthias Brugger,
moderated list:ARM/Mediatek SoC support,
moderated list:ARM/Mediatek SoC support
From: Yee Lee <yee.lee@mediatek.com>
Issue: hwtag kasan_unpoison() would overwrite the redzone in those object with unaligned object size. This patch Adds memzero_explict() to separate the initialization for such condition. The new code path is executed about 1.1% during nromal booting process.
=============
Exp: QEMUv5.2(+mte)/SLUB_debug
code path exec : 941/80854 (1.1%)
---
Changed since v1:
- Apply IS_ENABLED to wrap codes under SLUB debug mode.
- Replace memset() by memzero_explict().
---
Yee Lee (1):
kasan: Add memzero init for unaligned size under SLUB debug
mm/kasan/kasan.h | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
--
2.18.0
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^ permalink raw reply [flat|nested] 8+ messages in thread
* [PATCH v2 1/1] kasan: Add memzero init for unaligned size under SLUB debug
2021-06-23 13:35 [PATCH v2 0/1] kasan: fix redzone overwritten issue under SLUB debug yee.lee
@ 2021-06-23 13:35 ` yee.lee
2021-06-23 13:52 ` Yee Lee
2021-06-23 13:51 ` [PATCH v2 0/1] kasan: fix redzone overwritten issue " Yee Lee
1 sibling, 1 reply; 8+ messages in thread
From: yee.lee @ 2021-06-23 13:35 UTC (permalink / raw)
To: andreyknvl
Cc: wsd_upstream, Yee Lee, Andrey Ryabinin, Alexander Potapenko,
Dmitry Vyukov, Andrew Morton, Matthias Brugger, open list:KASAN,
open list:MEMORY MANAGEMENT, open list,
moderated list:ARM/Mediatek SoC support,
moderated list:ARM/Mediatek SoC support
From: Yee Lee <yee.lee@mediatek.com>
Issue: when SLUB debug is on, hwtag kasan_unpoison() would overwrite the redzone with unaligned object size.
An additional memzero_explicit() path is added to replacing hwtag initialization
at SLUB deubg mode.
Signed-off-by: Yee Lee <yee.lee@mediatek.com>
Suggested-by: Marco Elver <elver@google.com>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Andrey Konovalov <andreyknvl@gmail.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
---
mm/kasan/kasan.h | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/mm/kasan/kasan.h b/mm/kasan/kasan.h
index d8faa64614b7..e984a9ac814d 100644
--- a/mm/kasan/kasan.h
+++ b/mm/kasan/kasan.h
@@ -387,10 +387,12 @@ static inline void kasan_unpoison(const void *addr, size_t size, bool init)
if (WARN_ON((unsigned long)addr & KASAN_GRANULE_MASK))
return;
+ #if IS_ENABLED(CONFIG_SLUB_DEBUG)
if (init && ((unsigned long)size & KASAN_GRANULE_MASK)) {
init = false;
- memset((void *)addr, 0, size);
+ memzero_explicit((void *)addr, size);
}
+ #endif
size = round_up(size, KASAN_GRANULE_SIZE);
hw_set_mem_tag_range((void *)addr, size, tag, init);
}
--
2.18.0
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^ permalink raw reply related [flat|nested] 8+ messages in thread
* Re: [PATCH v2 0/1] kasan: fix redzone overwritten issue under SLUB debug
2021-06-23 13:35 [PATCH v2 0/1] kasan: fix redzone overwritten issue under SLUB debug yee.lee
2021-06-23 13:35 ` [PATCH v2 1/1] kasan: Add memzero init for unaligned size " yee.lee
@ 2021-06-23 13:51 ` Yee Lee
1 sibling, 0 replies; 8+ messages in thread
From: Yee Lee @ 2021-06-23 13:51 UTC (permalink / raw)
To: andreyknvl
Cc: wsd_upstream, Matthias Brugger,
moderated list:ARM/Mediatek SoC support,
moderated list:ARM/Mediatek SoC support
Sorry not a completed patch.
please skip this mail.
BR,
Yee
On Wed, 2021-06-23 at 21:35 +0800, yee.lee@mediatek.com wrote:
> From: Yee Lee <yee.lee@mediatek.com>
>
> Issue: hwtag kasan_unpoison() would overwrite the redzone in those
> object with unaligned object size. This patch Adds memzero_explict()
> to separate the initialization for such condition. The new code path
> is executed about 1.1% during nromal booting process.
>
> =============
> Exp: QEMUv5.2(+mte)/SLUB_debug
> code path exec : 941/80854 (1.1%)
>
> ---
> Changed since v1:
> - Apply IS_ENABLED to wrap codes under SLUB debug mode.
> - Replace memset() by memzero_explict().
>
> ---
> Yee Lee (1):
> kasan: Add memzero init for unaligned size under SLUB debug
>
> mm/kasan/kasan.h | 4 +++-
> 1 file changed, 3 insertions(+), 1 deletion(-)
>
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^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH v2 1/1] kasan: Add memzero init for unaligned size under SLUB debug
2021-06-23 13:35 ` [PATCH v2 1/1] kasan: Add memzero init for unaligned size " yee.lee
@ 2021-06-23 13:52 ` Yee Lee
0 siblings, 0 replies; 8+ messages in thread
From: Yee Lee @ 2021-06-23 13:52 UTC (permalink / raw)
To: andreyknvl
Cc: wsd_upstream, Andrey Ryabinin, Alexander Potapenko,
Dmitry Vyukov, Andrew Morton, Matthias Brugger, open list:KASAN,
open list:MEMORY MANAGEMENT, open list,
moderated list:ARM/Mediatek SoC support,
moderated list:ARM/Mediatek SoC support
Sorry not a completed patch.
Please skip this mail.
BR,
Yee
On Wed, 2021-06-23 at 21:35 +0800, 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 with unaligned object size.
>
> An additional memzero_explicit() path is added to replacing hwtag
> initialization
> at SLUB deubg mode.
>
> Signed-off-by: Yee Lee <yee.lee@mediatek.com>
> Suggested-by: Marco Elver <elver@google.com>
> Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
> Cc: Alexander Potapenko <glider@google.com>
> Cc: Andrey Konovalov <andreyknvl@gmail.com>
> Cc: Dmitry Vyukov <dvyukov@google.com>
> Cc: Andrew Morton <akpm@linux-foundation.org>
> ---
> mm/kasan/kasan.h | 4 +++-
> 1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/mm/kasan/kasan.h b/mm/kasan/kasan.h
> index d8faa64614b7..e984a9ac814d 100644
> --- a/mm/kasan/kasan.h
> +++ b/mm/kasan/kasan.h
> @@ -387,10 +387,12 @@ static inline void kasan_unpoison(const void
> *addr, size_t size, bool init)
>
> if (WARN_ON((unsigned long)addr & KASAN_GRANULE_MASK))
> return;
> + #if IS_ENABLED(CONFIG_SLUB_DEBUG)
> if (init && ((unsigned long)size & KASAN_GRANULE_MASK)) {
> init = false;
> - memset((void *)addr, 0, size);
> + memzero_explicit((void *)addr, size);
> }
> + #endif
> size = round_up(size, KASAN_GRANULE_SIZE);
> hw_set_mem_tag_range((void *)addr, size, tag, init);
> }
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^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH v2 1/1] kasan: Add memzero init for unaligned size under SLUB debug
2021-06-24 11:26 ` [PATCH v2 1/1] kasan: Add memzero init for unaligned size " yee.lee
2021-06-25 14:03 ` Andrey Konovalov
@ 2021-06-28 18:41 ` Marco Elver
1 sibling, 0 replies; 8+ messages in thread
From: Marco Elver @ 2021-06-28 18:41 UTC (permalink / raw)
To: yee.lee
Cc: andreyknvl, wsd_upstream, Andrey Ryabinin, Alexander Potapenko,
Dmitry Vyukov, Andrew Morton, Matthias Brugger, open list:KASAN,
open list:MEMORY MANAGEMENT, open list,
moderated list:ARM/Mediatek SoC support,
moderated list:ARM/Mediatek SoC support
On Thu, 24 Jun 2021 at 13:27, <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.
>
> Signed-off-by: Yee Lee <yee.lee@mediatek.com>
> ---
> mm/kasan/kasan.h | 6 ++++++
> 1 file changed, 6 insertions(+)
>
> diff --git a/mm/kasan/kasan.h b/mm/kasan/kasan.h
> index 8f450bc28045..d1054f35838f 100644
> --- a/mm/kasan/kasan.h
> +++ b/mm/kasan/kasan.h
> @@ -387,6 +387,12 @@ static inline void kasan_unpoison(const void *addr, size_t size, bool init)
>
> if (WARN_ON((unsigned long)addr & KASAN_GRANULE_MASK))
> return;
> +#if IS_ENABLED(CONFIG_SLUB_DEBUG)
Avoid the #if. I think none of the stuff referenced here is only
available if CONFIG_SLUB_DEBUG. In that case, please just write:
if (IS_ENABLED(CONFIG_SLUB_DEBUG) && init && .........) {
The compiler will correctly optimize out the branch if the config
option is not enabled. But the benefit is we compile-test this code
with all configs.
> + if (init && ((unsigned long)size & KASAN_GRANULE_MASK)) {
> + init = false;
> + memzero_explicit((void *)addr, size);
> + }
> +#endif
Thanks,
-- Marco
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^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH v2 1/1] kasan: Add memzero init for unaligned size under SLUB debug
2021-06-25 14:03 ` Andrey Konovalov
@ 2021-06-28 6:19 ` Yee Lee
0 siblings, 0 replies; 8+ messages in thread
From: Yee Lee @ 2021-06-28 6:19 UTC (permalink / raw)
To: Andrey Konovalov
Cc: wsd_upstream, Andrey Ryabinin, Alexander Potapenko,
Dmitry Vyukov, Andrew Morton, Matthias Brugger, open list:KASAN,
open list:MEMORY MANAGEMENT, open list,
moderated list:ARM/Mediatek SoC support,
moderated list:ARM/Mediatek SoC support
On Fri, 2021-06-25 at 17:03 +0300, Andrey Konovalov wrote:
> On Thu, Jun 24, 2021 at 2:26 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.
> >
> > Signed-off-by: Yee Lee <yee.lee@mediatek.com>
> > ---
> > mm/kasan/kasan.h | 6 ++++++
> > 1 file changed, 6 insertions(+)
> >
> > diff --git a/mm/kasan/kasan.h b/mm/kasan/kasan.h
> > index 8f450bc28045..d1054f35838f 100644
> > --- a/mm/kasan/kasan.h
> > +++ b/mm/kasan/kasan.h
> > @@ -387,6 +387,12 @@ static inline void kasan_unpoison(const void
> > *addr, size_t size, bool init)
> >
> > if (WARN_ON((unsigned long)addr & KASAN_GRANULE_MASK))
> > return;
> > +#if IS_ENABLED(CONFIG_SLUB_DEBUG)
>
> Is this an issue only with SLUB? SLAB also uses redzones.
As I known, hw-tag kasan only works with SLUB.
>
> > + if (init && ((unsigned long)size & KASAN_GRANULE_MASK)) {
>
> This needs a comment along the lines of:
>
> /* 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. */
Sure, will work on this.
>
> > + init = false;
> > + memzero_explicit((void *)addr, size);
> > + }
> > +#endif
> > size = round_up(size, KASAN_GRANULE_SIZE);
> >
> > hw_set_mem_tag_range((void *)addr, size, tag, init);
> > --
> > 2.18.0
> >
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^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH v2 1/1] kasan: Add memzero init for unaligned size under SLUB debug
2021-06-24 11:26 ` [PATCH v2 1/1] kasan: Add memzero init for unaligned size " yee.lee
@ 2021-06-25 14:03 ` Andrey Konovalov
2021-06-28 6:19 ` Yee Lee
2021-06-28 18:41 ` Marco Elver
1 sibling, 1 reply; 8+ messages in thread
From: Andrey Konovalov @ 2021-06-25 14:03 UTC (permalink / raw)
To: yee.lee
Cc: wsd_upstream, Andrey Ryabinin, Alexander Potapenko,
Dmitry Vyukov, Andrew Morton, Matthias Brugger, open list:KASAN,
open list:MEMORY MANAGEMENT, open list,
moderated list:ARM/Mediatek SoC support,
moderated list:ARM/Mediatek SoC support
On Thu, Jun 24, 2021 at 2:26 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.
>
> Signed-off-by: Yee Lee <yee.lee@mediatek.com>
> ---
> mm/kasan/kasan.h | 6 ++++++
> 1 file changed, 6 insertions(+)
>
> diff --git a/mm/kasan/kasan.h b/mm/kasan/kasan.h
> index 8f450bc28045..d1054f35838f 100644
> --- a/mm/kasan/kasan.h
> +++ b/mm/kasan/kasan.h
> @@ -387,6 +387,12 @@ static inline void kasan_unpoison(const void *addr, size_t size, bool init)
>
> if (WARN_ON((unsigned long)addr & KASAN_GRANULE_MASK))
> return;
> +#if IS_ENABLED(CONFIG_SLUB_DEBUG)
Is this an issue only with SLUB? SLAB also uses redzones.
> + if (init && ((unsigned long)size & KASAN_GRANULE_MASK)) {
This needs a comment along the lines of:
/* 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. */
> + init = false;
> + memzero_explicit((void *)addr, size);
> + }
> +#endif
> size = round_up(size, KASAN_GRANULE_SIZE);
>
> hw_set_mem_tag_range((void *)addr, size, tag, init);
> --
> 2.18.0
>
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^ permalink raw reply [flat|nested] 8+ messages in thread
* [PATCH v2 1/1] kasan: Add memzero init for unaligned size under SLUB debug
2021-06-24 11:26 yee.lee
@ 2021-06-24 11:26 ` yee.lee
2021-06-25 14:03 ` Andrey Konovalov
2021-06-28 18:41 ` Marco Elver
0 siblings, 2 replies; 8+ messages in thread
From: yee.lee @ 2021-06-24 11:26 UTC (permalink / raw)
To: andreyknvl
Cc: wsd_upstream, Yee Lee, Andrey Ryabinin, Alexander Potapenko,
Dmitry Vyukov, Andrew Morton, Matthias Brugger, open list:KASAN,
open list:MEMORY MANAGEMENT, open list,
moderated list:ARM/Mediatek SoC support,
moderated list:ARM/Mediatek SoC support
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.
Signed-off-by: Yee Lee <yee.lee@mediatek.com>
---
mm/kasan/kasan.h | 6 ++++++
1 file changed, 6 insertions(+)
diff --git a/mm/kasan/kasan.h b/mm/kasan/kasan.h
index 8f450bc28045..d1054f35838f 100644
--- a/mm/kasan/kasan.h
+++ b/mm/kasan/kasan.h
@@ -387,6 +387,12 @@ static inline void kasan_unpoison(const void *addr, size_t size, bool init)
if (WARN_ON((unsigned long)addr & KASAN_GRANULE_MASK))
return;
+#if IS_ENABLED(CONFIG_SLUB_DEBUG)
+ if (init && ((unsigned long)size & KASAN_GRANULE_MASK)) {
+ init = false;
+ memzero_explicit((void *)addr, size);
+ }
+#endif
size = round_up(size, KASAN_GRANULE_SIZE);
hw_set_mem_tag_range((void *)addr, size, tag, init);
--
2.18.0
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^ permalink raw reply related [flat|nested] 8+ messages in thread
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2021-06-23 13:35 [PATCH v2 0/1] kasan: fix redzone overwritten issue under SLUB debug yee.lee
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2021-06-23 13:52 ` Yee Lee
2021-06-23 13:51 ` [PATCH v2 0/1] kasan: fix redzone overwritten issue " Yee Lee
2021-06-24 11:26 yee.lee
2021-06-24 11:26 ` [PATCH v2 1/1] kasan: Add memzero init for unaligned size " yee.lee
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