* [PATCH v2 1/1] kasan: Add memzero init for unaligned size under SLUB debug [not found] <20210624112624.31215-1-yee.lee@mediatek.com> @ 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; 6+ 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 ^ permalink raw reply [flat|nested] 6+ 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 under SLUB debug 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; 6+ 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 > ^ permalink raw reply [flat|nested] 6+ 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; 6+ 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 > > ^ permalink raw reply [flat|nested] 6+ 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 under SLUB debug yee.lee 2021-06-25 14:03 ` Andrey Konovalov @ 2021-06-28 18:41 ` Marco Elver 1 sibling, 0 replies; 6+ 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 ^ permalink raw reply [flat|nested] 6+ messages in thread
[parent not found: <20210623133533.2246-1-yee.lee@mediatek.com>]
* [PATCH v2 1/1] kasan: Add memzero init for unaligned size under SLUB debug [not found] <20210623133533.2246-1-yee.lee@mediatek.com> @ 2021-06-23 13:35 ` yee.lee 2021-06-23 13:52 ` Yee Lee 0 siblings, 1 reply; 6+ 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 ^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH v2 1/1] kasan: Add memzero init for unaligned size under SLUB debug 2021-06-23 13:35 ` yee.lee @ 2021-06-23 13:52 ` Yee Lee 0 siblings, 0 replies; 6+ 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); > } ^ permalink raw reply [flat|nested] 6+ messages in thread
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2021-06-24 11:26 ` [PATCH v2 1/1] kasan: Add memzero init for unaligned size under SLUB debug yee.lee
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