From cde8a7eb778c7c71f70d636aa0bb1ec081b9167c Mon Sep 17 00:00:00 2001 From: Andrey Konovalov Date: Thu, 25 Feb 2021 17:20:27 -0800 Subject: [PATCH] kasan: ensure poisoning size alignment 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(). Link: https://lkml.kernel.org/r/3ffe8d4a246ae67a8b5e91f65bf98cd7cba9d7b9.1612546384.git.andreyknvl@google.com Signed-off-by: Andrey Konovalov Reviewed-by: Marco Elver Cc: Alexander Potapenko Cc: Andrey Ryabinin Cc: Branislav Rankov Cc: Catalin Marinas Cc: Dmitry Vyukov Cc: Evgenii Stepanov Cc: Kevin Brodsky Cc: Peter Collingbourne Cc: Vincenzo Frascino Cc: Will Deacon Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- 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 1e510649833b..dec7375fb884 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 222858e2e6af..8c55634d6edd 100644 --- a/mm/kasan/kasan.h +++ b/mm/kasan/kasan.h @@ -330,30 +330,37 @@ 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((unsigned long)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((unsigned long)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) @@ -370,7 +377,7 @@ 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. @@ -380,7 +387,7 @@ 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..63f43443f5d7 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((unsigned long)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((unsigned long)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 -- 2.20.1