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Wed, 03 Feb 2021 07:32:00 -0800 (PST) Date: Wed, 3 Feb 2021 16:31:54 +0100 From: Marco Elver To: Andrey Konovalov Cc: Catalin Marinas , Vincenzo Frascino , Dmitry Vyukov , Alexander Potapenko , Andrew Morton , Will Deacon , Andrey Ryabinin , Peter Collingbourne , Evgenii Stepanov , Branislav Rankov , Kevin Brodsky , kasan-dev@googlegroups.com, linux-arm-kernel@lists.infradead.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 09/12] kasan: ensure poisoning size alignment Message-ID: References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/2.0.2 (2020-11-20) X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Mon, Feb 01, 2021 at 08:43PM +0100, Andrey Konovalov wrote: > A previous changes d99f6a10c161 ("kasan: don't round_up too much") > attempted to simplify the code by adding a round_up(size) call into > kasan_poison(). While this allows to have less round_up() calls around > the code, this results in round_up() being called multiple times. > > This patch removes round_up() of size from kasan_poison() and ensures > that all callers round_up() the size explicitly. This patch also adds > WARN_ON() alignment checks for address and size to kasan_poison() and > kasan_unpoison(). > > Signed-off-by: Andrey Konovalov Reviewed-by: Marco Elver > --- > mm/kasan/common.c | 9 ++++++--- > mm/kasan/kasan.h | 33 ++++++++++++++++++++------------- > mm/kasan/shadow.c | 37 ++++++++++++++++++++++--------------- > 3 files changed, 48 insertions(+), 31 deletions(-) > > diff --git a/mm/kasan/common.c b/mm/kasan/common.c > index a51d6ea580b0..5691cca69397 100644 > --- a/mm/kasan/common.c > +++ b/mm/kasan/common.c > @@ -261,7 +261,8 @@ void __kasan_unpoison_object_data(struct kmem_cache *cache, void *object) > > void __kasan_poison_object_data(struct kmem_cache *cache, void *object) > { > - kasan_poison(object, cache->object_size, KASAN_KMALLOC_REDZONE); > + kasan_poison(object, round_up(cache->object_size, KASAN_GRANULE_SIZE), > + KASAN_KMALLOC_REDZONE); > } > > /* > @@ -348,7 +349,8 @@ static bool ____kasan_slab_free(struct kmem_cache *cache, void *object, > return true; > } > > - kasan_poison(object, cache->object_size, KASAN_KMALLOC_FREE); > + kasan_poison(object, round_up(cache->object_size, KASAN_GRANULE_SIZE), > + KASAN_KMALLOC_FREE); > > if ((IS_ENABLED(CONFIG_KASAN_GENERIC) && !quarantine)) > return false; > @@ -490,7 +492,8 @@ static void *____kasan_kmalloc(struct kmem_cache *cache, const void *object, > /* Poison the aligned part of the redzone. */ > redzone_start = round_up((unsigned long)(object + size), > KASAN_GRANULE_SIZE); > - redzone_end = (unsigned long)object + cache->object_size; > + redzone_end = round_up((unsigned long)(object + cache->object_size), > + KASAN_GRANULE_SIZE); > kasan_poison((void *)redzone_start, redzone_end - redzone_start, > KASAN_KMALLOC_REDZONE); > > diff --git a/mm/kasan/kasan.h b/mm/kasan/kasan.h > index 6a2882997f23..2f7400a3412f 100644 > --- a/mm/kasan/kasan.h > +++ b/mm/kasan/kasan.h > @@ -321,30 +321,37 @@ static inline u8 kasan_random_tag(void) { return 0; } > > #ifdef CONFIG_KASAN_HW_TAGS > > -static inline void kasan_poison(const void *address, size_t size, u8 value) > +static inline void kasan_poison(const void *addr, size_t size, u8 value) > { > - address = kasan_reset_tag(address); > + addr = kasan_reset_tag(addr); > > /* Skip KFENCE memory if called explicitly outside of sl*b. */ > - if (is_kfence_address(address)) > + if (is_kfence_address(addr)) > return; > > - hw_set_mem_tag_range((void *)address, > - round_up(size, KASAN_GRANULE_SIZE), value); > + if (WARN_ON((u64)addr & KASAN_GRANULE_MASK)) > + return; > + if (WARN_ON(size & KASAN_GRANULE_MASK)) > + return; > + > + hw_set_mem_tag_range((void *)addr, size, value); > } > > -static inline void kasan_unpoison(const void *address, size_t size) > +static inline void kasan_unpoison(const void *addr, size_t size) > { > - u8 tag = get_tag(address); > + u8 tag = get_tag(addr); > > - address = kasan_reset_tag(address); > + addr = kasan_reset_tag(addr); > > /* Skip KFENCE memory if called explicitly outside of sl*b. */ > - if (is_kfence_address(address)) > + if (is_kfence_address(addr)) > return; > > - hw_set_mem_tag_range((void *)address, > - round_up(size, KASAN_GRANULE_SIZE), tag); > + if (WARN_ON((u64)addr & KASAN_GRANULE_MASK)) > + return; > + size = round_up(size, KASAN_GRANULE_SIZE); > + > + hw_set_mem_tag_range((void *)addr, size, tag); > } > > static inline bool kasan_byte_accessible(const void *addr) > @@ -361,7 +368,7 @@ static inline bool kasan_byte_accessible(const void *addr) > /** > * kasan_poison - mark the memory range as unaccessible > * @addr - range start address, must be aligned to KASAN_GRANULE_SIZE > - * @size - range size > + * @size - range size, must be aligned to KASAN_GRANULE_SIZE > * @value - value that's written to metadata for the range > * > * The size gets aligned to KASAN_GRANULE_SIZE before marking the range. > @@ -371,7 +378,7 @@ void kasan_poison(const void *addr, size_t size, u8 value); > /** > * kasan_unpoison - mark the memory range as accessible > * @addr - range start address, must be aligned to KASAN_GRANULE_SIZE > - * @size - range size > + * @size - range size, can be unaligned > * > * For the tag-based modes, the @size gets aligned to KASAN_GRANULE_SIZE before > * marking the range. > diff --git a/mm/kasan/shadow.c b/mm/kasan/shadow.c > index 1ed7817e4ee6..c97f51c557ea 100644 > --- a/mm/kasan/shadow.c > +++ b/mm/kasan/shadow.c > @@ -69,7 +69,7 @@ void *memcpy(void *dest, const void *src, size_t len) > return __memcpy(dest, src, len); > } > > -void kasan_poison(const void *address, size_t size, u8 value) > +void kasan_poison(const void *addr, size_t size, u8 value) > { > void *shadow_start, *shadow_end; > > @@ -78,55 +78,62 @@ void kasan_poison(const void *address, size_t size, u8 value) > * some of the callers (e.g. kasan_poison_object_data) pass tagged > * addresses to this function. > */ > - address = kasan_reset_tag(address); > + addr = kasan_reset_tag(addr); > > /* Skip KFENCE memory if called explicitly outside of sl*b. */ > - if (is_kfence_address(address)) > + if (is_kfence_address(addr)) > return; > > - size = round_up(size, KASAN_GRANULE_SIZE); > - shadow_start = kasan_mem_to_shadow(address); > - shadow_end = kasan_mem_to_shadow(address + size); > + if (WARN_ON((u64)addr & KASAN_GRANULE_MASK)) > + return; > + if (WARN_ON(size & KASAN_GRANULE_MASK)) > + return; > + > + shadow_start = kasan_mem_to_shadow(addr); > + shadow_end = kasan_mem_to_shadow(addr + size); > > __memset(shadow_start, value, shadow_end - shadow_start); > } > EXPORT_SYMBOL(kasan_poison); > > #ifdef CONFIG_KASAN_GENERIC > -void kasan_poison_last_granule(const void *address, size_t size) > +void kasan_poison_last_granule(const void *addr, size_t size) > { > if (size & KASAN_GRANULE_MASK) { > - u8 *shadow = (u8 *)kasan_mem_to_shadow(address + size); > + u8 *shadow = (u8 *)kasan_mem_to_shadow(addr + size); > *shadow = size & KASAN_GRANULE_MASK; > } > } > #endif > > -void kasan_unpoison(const void *address, size_t size) > +void kasan_unpoison(const void *addr, size_t size) > { > - u8 tag = get_tag(address); > + u8 tag = get_tag(addr); > > /* > * Perform shadow offset calculation based on untagged address, as > * some of the callers (e.g. kasan_unpoison_object_data) pass tagged > * addresses to this function. > */ > - address = kasan_reset_tag(address); > + addr = kasan_reset_tag(addr); > > /* > * Skip KFENCE memory if called explicitly outside of sl*b. Also note > * that calls to ksize(), where size is not a multiple of machine-word > * size, would otherwise poison the invalid portion of the word. > */ > - if (is_kfence_address(address)) > + if (is_kfence_address(addr)) > + return; > + > + if (WARN_ON((u64)addr & KASAN_GRANULE_MASK)) > return; > > - /* Unpoison round_up(size, KASAN_GRANULE_SIZE) bytes. */ > - kasan_poison(address, size, tag); > + /* Unpoison all granules that cover the object. */ > + kasan_poison(addr, round_up(size, KASAN_GRANULE_SIZE), tag); > > /* Partially poison the last granule for the generic mode. */ > if (IS_ENABLED(CONFIG_KASAN_GENERIC)) > - kasan_poison_last_granule(address, size); > + kasan_poison_last_granule(addr, size); > } > > #ifdef CONFIG_MEMORY_HOTPLUG > -- > 2.30.0.365.g02bc693789-goog >