From: Andrey Konovalov <andreyknvl@xxxxxxxxxx>
Subject: 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@xxxxxxxxxx
Signed-off-by: Andrey Konovalov <andreyknvl@xxxxxxxxxx>
Reviewed-by: Marco Elver <elver@xxxxxxxxxx>
Cc: Alexander Potapenko <glider@xxxxxxxxxx>
Cc: Andrey Ryabinin <aryabinin@xxxxxxxxxxxxx>
Cc: Branislav Rankov <Branislav.Rankov@xxxxxxx>
Cc: Catalin Marinas <catalin.marinas@xxxxxxx>
Cc: Dmitry Vyukov <dvyukov@xxxxxxxxxx>
Cc: Evgenii Stepanov <eugenis@xxxxxxxxxx>
Cc: Kevin Brodsky <kevin.brodsky@xxxxxxx>
Cc: Peter Collingbourne <pcc@xxxxxxxxxx>
Cc: Vincenzo Frascino <vincenzo.frascino@xxxxxxx>
Cc: Will Deacon <will.deacon@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/kasan/common.c | 9 ++++++---
mm/kasan/kasan.h | 33 ++++++++++++++++++++-------------
mm/kasan/shadow.c | 37 ++++++++++++++++++++++---------------
3 files changed, 48 insertions(+), 31 deletions(-)
--- a/mm/kasan/common.c~kasan-ensure-poisoning-size-alignment
+++ a/mm/kasan/common.c
@@ -261,7 +261,8 @@ void __kasan_unpoison_object_data(struct
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 k
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 km
/* 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);
--- a/mm/kasan/kasan.h~kasan-ensure-poisoning-size-alignment
+++ a/mm/kasan/kasan.h
@@ -330,30 +330,37 @@ static inline u8 kasan_random_tag(void)
#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;
+
+ if (WARN_ON((unsigned long)addr & KASAN_GRANULE_MASK))
return;
+ size = round_up(size, KASAN_GRANULE_SIZE);
- hw_set_mem_tag_range((void *)address,
- round_up(size, KASAN_GRANULE_SIZE), tag);
+ 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
/**
* 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
/**
* 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.
--- a/mm/kasan/shadow.c~kasan-ensure-poisoning-size-alignment
+++ a/mm/kasan/shadow.c
@@ -69,7 +69,7 @@ void *memcpy(void *dest, const void *src
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, s
* 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
_
