[PATCH v3 12/12] kasan: add shadow checks to wrappers and rename kasan_arch_is_ready
Sabyrzhan Tasbolatov
snovitoll at gmail.com
Thu Jul 17 07:27:32 PDT 2025
This patch completes:
1. Adding kasan_shadow_initialized() checks to existing wrapper functions
2. Replacing kasan_arch_is_ready() calls with kasan_shadow_initialized()
3. Creating wrapper functions for internal functions that need shadow
readiness checks
4. Removing the kasan_arch_is_ready() fallback definition
The two-level approach is now fully implemented:
- kasan_enabled() - controls whether KASAN is enabled at all.
(compile-time for most archs)
- kasan_shadow_initialized() - tracks shadow memory initialization
(static key for ARCH_DEFER_KASAN archs, compile-time for others)
This provides complete elimination of kasan_arch_is_ready() calls from
KASAN implementation while moving all shadow readiness logic to
wrapper functions.
Closes: https://bugzilla.kernel.org/show_bug.cgi?id=217049
Signed-off-by: Sabyrzhan Tasbolatov <snovitoll at gmail.com>
---
Changes in v3:
- Addresses Andrey's feedback to move shadow checks to wrappers
- Rename kasan_arch_is_ready with kasan_shadow_initialized
- Added kasan_shadow_initialized() checks to all necessary wrapper functions
- Eliminated all remaining kasan_arch_is_ready() usage per reviewer guidance
---
include/linux/kasan.h | 36 +++++++++++++++++++++++++++---------
mm/kasan/common.c | 9 +++------
mm/kasan/generic.c | 12 +++---------
mm/kasan/kasan.h | 36 ++++++++++++++++++++++++++----------
mm/kasan/shadow.c | 32 +++++++-------------------------
5 files changed, 66 insertions(+), 59 deletions(-)
diff --git a/include/linux/kasan.h b/include/linux/kasan.h
index 51a8293d1af..292bd741d8d 100644
--- a/include/linux/kasan.h
+++ b/include/linux/kasan.h
@@ -194,7 +194,7 @@ bool __kasan_slab_pre_free(struct kmem_cache *s, void *object,
static __always_inline bool kasan_slab_pre_free(struct kmem_cache *s,
void *object)
{
- if (kasan_enabled())
+ if (kasan_enabled() && kasan_shadow_initialized())
return __kasan_slab_pre_free(s, object, _RET_IP_);
return false;
}
@@ -229,7 +229,7 @@ static __always_inline bool kasan_slab_free(struct kmem_cache *s,
void *object, bool init,
bool still_accessible)
{
- if (kasan_enabled())
+ if (kasan_enabled() && kasan_shadow_initialized())
return __kasan_slab_free(s, object, init, still_accessible);
return false;
}
@@ -237,7 +237,7 @@ static __always_inline bool kasan_slab_free(struct kmem_cache *s,
void __kasan_kfree_large(void *ptr, unsigned long ip);
static __always_inline void kasan_kfree_large(void *ptr)
{
- if (kasan_enabled())
+ if (kasan_enabled() && kasan_shadow_initialized())
__kasan_kfree_large(ptr, _RET_IP_);
}
@@ -302,7 +302,7 @@ bool __kasan_mempool_poison_pages(struct page *page, unsigned int order,
static __always_inline bool kasan_mempool_poison_pages(struct page *page,
unsigned int order)
{
- if (kasan_enabled())
+ if (kasan_enabled() && kasan_shadow_initialized())
return __kasan_mempool_poison_pages(page, order, _RET_IP_);
return true;
}
@@ -356,7 +356,7 @@ bool __kasan_mempool_poison_object(void *ptr, unsigned long ip);
*/
static __always_inline bool kasan_mempool_poison_object(void *ptr)
{
- if (kasan_enabled())
+ if (kasan_enabled() && kasan_shadow_initialized())
return __kasan_mempool_poison_object(ptr, _RET_IP_);
return true;
}
@@ -568,11 +568,29 @@ static inline void kasan_init_hw_tags(void) { }
#if defined(CONFIG_KASAN_GENERIC) || defined(CONFIG_KASAN_SW_TAGS)
void kasan_populate_early_vm_area_shadow(void *start, unsigned long size);
-int kasan_populate_vmalloc(unsigned long addr, unsigned long size);
-void kasan_release_vmalloc(unsigned long start, unsigned long end,
+
+int __kasan_populate_vmalloc(unsigned long addr, unsigned long size);
+static inline int kasan_populate_vmalloc(unsigned long addr, unsigned long size)
+{
+ if (!kasan_shadow_initialized())
+ return 0;
+ return __kasan_populate_vmalloc(addr, size);
+}
+
+void __kasan_release_vmalloc(unsigned long start, unsigned long end,
unsigned long free_region_start,
unsigned long free_region_end,
unsigned long flags);
+static inline void kasan_release_vmalloc(unsigned long start,
+ unsigned long end,
+ unsigned long free_region_start,
+ unsigned long free_region_end,
+ unsigned long flags)
+{
+ if (kasan_shadow_initialized())
+ __kasan_release_vmalloc(start, end, free_region_start,
+ free_region_end, flags);
+}
#else /* CONFIG_KASAN_GENERIC || CONFIG_KASAN_SW_TAGS */
@@ -598,7 +616,7 @@ static __always_inline void *kasan_unpoison_vmalloc(const void *start,
unsigned long size,
kasan_vmalloc_flags_t flags)
{
- if (kasan_enabled())
+ if (kasan_enabled() && kasan_shadow_initialized())
return __kasan_unpoison_vmalloc(start, size, flags);
return (void *)start;
}
@@ -607,7 +625,7 @@ void __kasan_poison_vmalloc(const void *start, unsigned long size);
static __always_inline void kasan_poison_vmalloc(const void *start,
unsigned long size)
{
- if (kasan_enabled())
+ if (kasan_enabled() && kasan_shadow_initialized())
__kasan_poison_vmalloc(start, size);
}
diff --git a/mm/kasan/common.c b/mm/kasan/common.c
index c3a6446404d..b561734767d 100644
--- a/mm/kasan/common.c
+++ b/mm/kasan/common.c
@@ -259,7 +259,7 @@ static inline void poison_slab_object(struct kmem_cache *cache, void *object,
bool __kasan_slab_pre_free(struct kmem_cache *cache, void *object,
unsigned long ip)
{
- if (!kasan_arch_is_ready() || is_kfence_address(object))
+ if (is_kfence_address(object))
return false;
return check_slab_allocation(cache, object, ip);
}
@@ -267,7 +267,7 @@ bool __kasan_slab_pre_free(struct kmem_cache *cache, void *object,
bool __kasan_slab_free(struct kmem_cache *cache, void *object, bool init,
bool still_accessible)
{
- if (!kasan_arch_is_ready() || is_kfence_address(object))
+ if (is_kfence_address(object))
return false;
poison_slab_object(cache, object, init, still_accessible);
@@ -291,9 +291,6 @@ bool __kasan_slab_free(struct kmem_cache *cache, void *object, bool init,
static inline bool check_page_allocation(void *ptr, unsigned long ip)
{
- if (!kasan_arch_is_ready())
- return false;
-
if (ptr != page_address(virt_to_head_page(ptr))) {
kasan_report_invalid_free(ptr, ip, KASAN_REPORT_INVALID_FREE);
return true;
@@ -520,7 +517,7 @@ bool __kasan_mempool_poison_object(void *ptr, unsigned long ip)
return true;
}
- if (is_kfence_address(ptr) || !kasan_arch_is_ready())
+ if (is_kfence_address(ptr))
return true;
slab = folio_slab(folio);
diff --git a/mm/kasan/generic.c b/mm/kasan/generic.c
index 03b6d322ff6..1d20b925b9d 100644
--- a/mm/kasan/generic.c
+++ b/mm/kasan/generic.c
@@ -176,7 +176,7 @@ static __always_inline bool check_region_inline(const void *addr,
size_t size, bool write,
unsigned long ret_ip)
{
- if (!kasan_arch_is_ready())
+ if (!kasan_shadow_initialized())
return true;
if (unlikely(size == 0))
@@ -200,13 +200,10 @@ bool kasan_check_range(const void *addr, size_t size, bool write,
return check_region_inline(addr, size, write, ret_ip);
}
-bool kasan_byte_accessible(const void *addr)
+bool __kasan_byte_accessible(const void *addr)
{
s8 shadow_byte;
- if (!kasan_arch_is_ready())
- return true;
-
shadow_byte = READ_ONCE(*(s8 *)kasan_mem_to_shadow(addr));
return shadow_byte >= 0 && shadow_byte < KASAN_GRANULE_SIZE;
@@ -506,9 +503,6 @@ static void release_alloc_meta(struct kasan_alloc_meta *meta)
static void release_free_meta(const void *object, struct kasan_free_meta *meta)
{
- if (!kasan_arch_is_ready())
- return;
-
/* Check if free meta is valid. */
if (*(u8 *)kasan_mem_to_shadow(object) != KASAN_SLAB_FREE_META)
return;
@@ -573,7 +567,7 @@ void kasan_save_alloc_info(struct kmem_cache *cache, void *object, gfp_t flags)
kasan_save_track(&alloc_meta->alloc_track, flags);
}
-void kasan_save_free_info(struct kmem_cache *cache, void *object)
+void __kasan_save_free_info(struct kmem_cache *cache, void *object)
{
struct kasan_free_meta *free_meta;
diff --git a/mm/kasan/kasan.h b/mm/kasan/kasan.h
index 129178be5e6..67a0a1095d2 100644
--- a/mm/kasan/kasan.h
+++ b/mm/kasan/kasan.h
@@ -398,7 +398,13 @@ depot_stack_handle_t kasan_save_stack(gfp_t flags, depot_flags_t depot_flags);
void kasan_set_track(struct kasan_track *track, depot_stack_handle_t stack);
void kasan_save_track(struct kasan_track *track, gfp_t flags);
void kasan_save_alloc_info(struct kmem_cache *cache, void *object, gfp_t flags);
-void kasan_save_free_info(struct kmem_cache *cache, void *object);
+
+void __kasan_save_free_info(struct kmem_cache *cache, void *object);
+static inline void kasan_save_free_info(struct kmem_cache *cache, void *object)
+{
+ if (kasan_enabled() && kasan_shadow_initialized())
+ __kasan_save_free_info(cache, object);
+}
#ifdef CONFIG_KASAN_GENERIC
bool kasan_quarantine_put(struct kmem_cache *cache, void *object);
@@ -499,6 +505,7 @@ static inline bool kasan_byte_accessible(const void *addr)
#else /* CONFIG_KASAN_HW_TAGS */
+void __kasan_poison(const void *addr, size_t size, u8 value, bool init);
/**
* kasan_poison - mark the memory range as inaccessible
* @addr: range start address, must be aligned to KASAN_GRANULE_SIZE
@@ -506,7 +513,11 @@ static inline bool kasan_byte_accessible(const void *addr)
* @value: value that's written to metadata for the range
* @init: whether to initialize the memory range (only for hardware tag-based)
*/
-void kasan_poison(const void *addr, size_t size, u8 value, bool init);
+static inline void kasan_poison(const void *addr, size_t size, u8 value, bool init)
+{
+ if (kasan_shadow_initialized())
+ __kasan_poison(addr, size, value, init);
+}
/**
* kasan_unpoison - mark the memory range as accessible
@@ -521,12 +532,19 @@ void kasan_poison(const void *addr, size_t size, u8 value, bool init);
*/
void kasan_unpoison(const void *addr, size_t size, bool init);
-bool kasan_byte_accessible(const void *addr);
+bool __kasan_byte_accessible(const void *addr);
+static inline bool kasan_byte_accessible(const void *addr)
+{
+ if (!kasan_shadow_initialized())
+ return true;
+ return __kasan_byte_accessible(addr);
+}
#endif /* CONFIG_KASAN_HW_TAGS */
#ifdef CONFIG_KASAN_GENERIC
+void __kasan_poison_last_granule(const void *address, size_t size);
/**
* kasan_poison_last_granule - mark the last granule of the memory range as
* inaccessible
@@ -536,7 +554,11 @@ bool kasan_byte_accessible(const void *addr);
* This function is only available for the generic mode, as it's the only mode
* that has partially poisoned memory granules.
*/
-void kasan_poison_last_granule(const void *address, size_t size);
+static inline void kasan_poison_last_granule(const void *address, size_t size)
+{
+ if (kasan_shadow_initialized())
+ __kasan_poison_last_granule(address, size);
+}
#else /* CONFIG_KASAN_GENERIC */
@@ -544,12 +566,6 @@ static inline void kasan_poison_last_granule(const void *address, size_t size) {
#endif /* CONFIG_KASAN_GENERIC */
-#ifndef kasan_arch_is_ready
-static inline bool kasan_arch_is_ready(void) { return true; }
-#elif !defined(CONFIG_KASAN_GENERIC) || !defined(CONFIG_KASAN_OUTLINE)
-#error kasan_arch_is_ready only works in KASAN generic outline mode!
-#endif
-
#if IS_ENABLED(CONFIG_KASAN_KUNIT_TEST)
void kasan_kunit_test_suite_start(void);
diff --git a/mm/kasan/shadow.c b/mm/kasan/shadow.c
index d2c70cd2afb..90c508cad63 100644
--- a/mm/kasan/shadow.c
+++ b/mm/kasan/shadow.c
@@ -121,13 +121,10 @@ void *__hwasan_memcpy(void *dest, const void *src, ssize_t len) __alias(__asan_m
EXPORT_SYMBOL(__hwasan_memcpy);
#endif
-void kasan_poison(const void *addr, size_t size, u8 value, bool init)
+void __kasan_poison(const void *addr, size_t size, u8 value, bool init)
{
void *shadow_start, *shadow_end;
- if (!kasan_arch_is_ready())
- return;
-
/*
* Perform shadow offset calculation based on untagged address, as
* some of the callers (e.g. kasan_poison_new_object) pass tagged
@@ -145,14 +142,11 @@ void kasan_poison(const void *addr, size_t size, u8 value, bool init)
__memset(shadow_start, value, shadow_end - shadow_start);
}
-EXPORT_SYMBOL_GPL(kasan_poison);
+EXPORT_SYMBOL_GPL(__kasan_poison);
#ifdef CONFIG_KASAN_GENERIC
-void kasan_poison_last_granule(const void *addr, size_t size)
+void __kasan_poison_last_granule(const void *addr, size_t size)
{
- if (!kasan_arch_is_ready())
- return;
-
if (size & KASAN_GRANULE_MASK) {
u8 *shadow = (u8 *)kasan_mem_to_shadow(addr + size);
*shadow = size & KASAN_GRANULE_MASK;
@@ -353,7 +347,7 @@ static int ___alloc_pages_bulk(struct page **pages, int nr_pages)
return 0;
}
-static int __kasan_populate_vmalloc(unsigned long start, unsigned long end)
+static int __kasan_populate_vmalloc_do(unsigned long start, unsigned long end)
{
unsigned long nr_pages, nr_total = PFN_UP(end - start);
struct vmalloc_populate_data data;
@@ -385,14 +379,11 @@ static int __kasan_populate_vmalloc(unsigned long start, unsigned long end)
return ret;
}
-int kasan_populate_vmalloc(unsigned long addr, unsigned long size)
+int __kasan_populate_vmalloc(unsigned long addr, unsigned long size)
{
unsigned long shadow_start, shadow_end;
int ret;
- if (!kasan_arch_is_ready())
- return 0;
-
if (!is_vmalloc_or_module_addr((void *)addr))
return 0;
@@ -414,7 +405,7 @@ int kasan_populate_vmalloc(unsigned long addr, unsigned long size)
shadow_start = PAGE_ALIGN_DOWN(shadow_start);
shadow_end = PAGE_ALIGN(shadow_end);
- ret = __kasan_populate_vmalloc(shadow_start, shadow_end);
+ ret = __kasan_populate_vmalloc_do(shadow_start, shadow_end);
if (ret)
return ret;
@@ -551,7 +542,7 @@ static int kasan_depopulate_vmalloc_pte(pte_t *ptep, unsigned long addr,
* pages entirely covered by the free region, we will not run in to any
* trouble - any simultaneous allocations will be for disjoint regions.
*/
-void kasan_release_vmalloc(unsigned long start, unsigned long end,
+void __kasan_release_vmalloc(unsigned long start, unsigned long end,
unsigned long free_region_start,
unsigned long free_region_end,
unsigned long flags)
@@ -560,9 +551,6 @@ void kasan_release_vmalloc(unsigned long start, unsigned long end,
unsigned long region_start, region_end;
unsigned long size;
- if (!kasan_arch_is_ready())
- return;
-
region_start = ALIGN(start, KASAN_MEMORY_PER_SHADOW_PAGE);
region_end = ALIGN_DOWN(end, KASAN_MEMORY_PER_SHADOW_PAGE);
@@ -611,9 +599,6 @@ void *__kasan_unpoison_vmalloc(const void *start, unsigned long size,
* with setting memory tags, so the KASAN_VMALLOC_INIT flag is ignored.
*/
- if (!kasan_arch_is_ready())
- return (void *)start;
-
if (!is_vmalloc_or_module_addr(start))
return (void *)start;
@@ -636,9 +621,6 @@ void *__kasan_unpoison_vmalloc(const void *start, unsigned long size,
*/
void __kasan_poison_vmalloc(const void *start, unsigned long size)
{
- if (!kasan_arch_is_ready())
- return;
-
if (!is_vmalloc_or_module_addr(start))
return;
--
2.34.1
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