From 10d1f8cb3965a6f633bf23eb984cda552927e3a5 Mon Sep 17 00:00:00 2001 From: Marco Elver Date: Thu, 11 Jul 2019 20:54:14 -0700 Subject: [PATCH] mm/slab: refactor common ksize KASAN logic into slab_common.c This refactors common code of ksize() between the various allocators into slab_common.c: __ksize() is the allocator-specific implementation without instrumentation, whereas ksize() includes the required KASAN logic. Link: http://lkml.kernel.org/r/20190626142014.141844-5-elver@google.com Signed-off-by: Marco Elver Acked-by: Christoph Lameter Reviewed-by: Andrey Ryabinin Cc: Dmitry Vyukov Cc: Alexander Potapenko Cc: Andrey Konovalov Cc: Pekka Enberg Cc: David Rientjes Cc: Joonsoo Kim Cc: Mark Rutland Cc: Kees Cook Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/slab.h | 1 + mm/slab.c | 22 +++++----------------- mm/slab_common.c | 26 ++++++++++++++++++++++++++ mm/slob.c | 4 ++-- mm/slub.c | 14 ++------------ 5 files changed, 36 insertions(+), 31 deletions(-) diff --git a/include/linux/slab.h b/include/linux/slab.h index 9449b19c5f10..98c3d12b7275 100644 --- a/include/linux/slab.h +++ b/include/linux/slab.h @@ -184,6 +184,7 @@ void * __must_check __krealloc(const void *, size_t, gfp_t); void * __must_check krealloc(const void *, size_t, gfp_t); void kfree(const void *); void kzfree(const void *); +size_t __ksize(const void *); size_t ksize(const void *); #ifdef CONFIG_HAVE_HARDENED_USERCOPY_ALLOCATOR diff --git a/mm/slab.c b/mm/slab.c index db01e9aae31b..3521a351ceb5 100644 --- a/mm/slab.c +++ b/mm/slab.c @@ -4204,20 +4204,12 @@ void __check_heap_object(const void *ptr, unsigned long n, struct page *page, #endif /* CONFIG_HARDENED_USERCOPY */ /** - * ksize - get the actual amount of memory allocated for a given object - * @objp: Pointer to the object + * __ksize -- Uninstrumented ksize. * - * kmalloc may internally round up allocations and return more memory - * than requested. ksize() can be used to determine the actual amount of - * memory allocated. The caller may use this additional memory, even though - * a smaller amount of memory was initially specified with the kmalloc call. - * The caller must guarantee that objp points to a valid object previously - * allocated with either kmalloc() or kmem_cache_alloc(). The object - * must not be freed during the duration of the call. - * - * Return: size of the actual memory used by @objp in bytes + * Unlike ksize(), __ksize() is uninstrumented, and does not provide the same + * safety checks as ksize() with KASAN instrumentation enabled. */ -size_t ksize(const void *objp) +size_t __ksize(const void *objp) { struct kmem_cache *c; size_t size; @@ -4228,11 +4220,7 @@ size_t ksize(const void *objp) c = virt_to_cache(objp); size = c ? c->object_size : 0; - /* We assume that ksize callers could use the whole allocated area, - * so we need to unpoison this area. - */ - kasan_unpoison_shadow(objp, size); return size; } -EXPORT_SYMBOL(ksize); +EXPORT_SYMBOL(__ksize); diff --git a/mm/slab_common.c b/mm/slab_common.c index 58251ba63e4a..b7c6a40e436a 100644 --- a/mm/slab_common.c +++ b/mm/slab_common.c @@ -1597,6 +1597,32 @@ void kzfree(const void *p) } EXPORT_SYMBOL(kzfree); +/** + * ksize - get the actual amount of memory allocated for a given object + * @objp: Pointer to the object + * + * kmalloc may internally round up allocations and return more memory + * than requested. ksize() can be used to determine the actual amount of + * memory allocated. The caller may use this additional memory, even though + * a smaller amount of memory was initially specified with the kmalloc call. + * The caller must guarantee that objp points to a valid object previously + * allocated with either kmalloc() or kmem_cache_alloc(). The object + * must not be freed during the duration of the call. + * + * Return: size of the actual memory used by @objp in bytes + */ +size_t ksize(const void *objp) +{ + size_t size = __ksize(objp); + /* + * We assume that ksize callers could use whole allocated area, + * so we need to unpoison this area. + */ + kasan_unpoison_shadow(objp, size); + return size; +} +EXPORT_SYMBOL(ksize); + /* Tracepoints definitions. */ EXPORT_TRACEPOINT_SYMBOL(kmalloc); EXPORT_TRACEPOINT_SYMBOL(kmem_cache_alloc); diff --git a/mm/slob.c b/mm/slob.c index 84aefd9b91ee..7f421d0ca9ab 100644 --- a/mm/slob.c +++ b/mm/slob.c @@ -527,7 +527,7 @@ void kfree(const void *block) EXPORT_SYMBOL(kfree); /* can't use ksize for kmem_cache_alloc memory, only kmalloc */ -size_t ksize(const void *block) +size_t __ksize(const void *block) { struct page *sp; int align; @@ -545,7 +545,7 @@ size_t ksize(const void *block) m = (unsigned int *)(block - align); return SLOB_UNITS(*m) * SLOB_UNIT; } -EXPORT_SYMBOL(ksize); +EXPORT_SYMBOL(__ksize); int __kmem_cache_create(struct kmem_cache *c, slab_flags_t flags) { diff --git a/mm/slub.c b/mm/slub.c index d46a91759b96..5e217653286c 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -3895,7 +3895,7 @@ void __check_heap_object(const void *ptr, unsigned long n, struct page *page, } #endif /* CONFIG_HARDENED_USERCOPY */ -static size_t __ksize(const void *object) +size_t __ksize(const void *object) { struct page *page; @@ -3911,17 +3911,7 @@ static size_t __ksize(const void *object) return slab_ksize(page->slab_cache); } - -size_t ksize(const void *object) -{ - size_t size = __ksize(object); - /* We assume that ksize callers could use whole allocated area, - * so we need to unpoison this area. - */ - kasan_unpoison_shadow(object, size); - return size; -} -EXPORT_SYMBOL(ksize); +EXPORT_SYMBOL(__ksize); void kfree(const void *x) {