Commit 3b7f8813 authored by Andrey Konovalov's avatar Andrey Konovalov Committed by Andrew Morton
Browse files

kasan: only define kasan_never_merge for Generic mode 

KASAN prevents merging of slab caches whose objects have per-object
metadata stored in redzones.

As now only the Generic mode uses per-object metadata, define
kasan_never_merge() only for this mode.

Link: https://lkml.kernel.org/r/81ed01f29ff3443580b7e2fe362a8b47b1e8006d.1662411799.git.andreyknvl@google.com


Signed-off-by: default avatarAndrey Konovalov <andreyknvl@google.com>
Reviewed-by: default avatarMarco Elver <elver@google.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Evgenii Stepanov <eugenis@google.com>
Cc: Peter Collingbourne <pcc@google.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent f372bde9

include/linux/kasan.h

+6 −12
Original line number Diff line number Diff line
@@ -103,14 +103,6 @@ struct kasan_cache { 
	bool is_kmalloc;

};



slab_flags_t __kasan_never_merge(void);

static __always_inline slab_flags_t kasan_never_merge(void)

{

	if (kasan_enabled())

		return __kasan_never_merge();

	return 0;

}



void __kasan_unpoison_range(const void *addr, size_t size);

static __always_inline void kasan_unpoison_range(const void *addr, size_t size)

{
@@ -261,10 +253,6 @@ static __always_inline bool kasan_check_byte(const void *addr) 


#else /* CONFIG_KASAN */



static inline slab_flags_t kasan_never_merge(void)

{

	return 0;

}

static inline void kasan_unpoison_range(const void *address, size_t size) {}

static inline void kasan_poison_pages(struct page *page, unsigned int order,

				      bool init) {}
@@ -325,6 +313,7 @@ static inline void kasan_unpoison_task_stack(struct task_struct *task) {} 
#ifdef CONFIG_KASAN_GENERIC



size_t kasan_metadata_size(struct kmem_cache *cache);

slab_flags_t kasan_never_merge(void);



void kasan_cache_shrink(struct kmem_cache *cache);

void kasan_cache_shutdown(struct kmem_cache *cache);
@@ -338,6 +327,11 @@ static inline size_t kasan_metadata_size(struct kmem_cache *cache) 
{

	return 0;

}

/* And thus nothing prevents cache merging. */

static inline slab_flags_t kasan_never_merge(void)

{

	return 0;

}



static inline void kasan_cache_shrink(struct kmem_cache *cache) {}

static inline void kasan_cache_shutdown(struct kmem_cache *cache) {}

mm/kasan/common.c

+0 −8
Original line number Diff line number Diff line
@@ -88,14 +88,6 @@ asmlinkage void kasan_unpoison_task_stack_below(const void *watermark) 
}

#endif /* CONFIG_KASAN_STACK */



/* Only allow cache merging when no per-object metadata is present. */

slab_flags_t __kasan_never_merge(void)

{

	if (kasan_requires_meta())

		return SLAB_KASAN;

	return 0;

}



void __kasan_unpoison_pages(struct page *page, unsigned int order, bool init)

{

	u8 tag;

mm/kasan/generic.c

+8 −0
Original line number Diff line number Diff line
@@ -328,6 +328,14 @@ DEFINE_ASAN_SET_SHADOW(f3); 
DEFINE_ASAN_SET_SHADOW(f5);

DEFINE_ASAN_SET_SHADOW(f8);



/* Only allow cache merging when no per-object metadata is present. */

slab_flags_t kasan_never_merge(void)

{

	if (!kasan_requires_meta())

		return 0;

	return SLAB_KASAN;

}



/*

 * Adaptive redzone policy taken from the userspace AddressSanitizer runtime.

 * For larger allocations larger redzones are used.