[PATCH 3/5] mm/page_alloc: Add __alloc_size attributes for better bounds checking

From: Kees Cook
Date: Wed Aug 18 2021 - 01:09:01 EST

As already done in GrapheneOS, add the __alloc_size attribute for
appropriate page allocator interfaces, to provide additional hinting
for better bounds checking, assisting CONFIG_FORTIFY_SOURCE and other
compiler optimizations.

Co-developed-by: Daniel Micay <danielmicay@xxxxxxxxx>
Signed-off-by: Daniel Micay <danielmicay@xxxxxxxxx>
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: linux-mm@xxxxxxxxx
Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx>
include/linux/gfp.h | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/include/linux/gfp.h b/include/linux/gfp.h
index 3745efd21cf6..94e57c752308 100644
--- a/include/linux/gfp.h
+++ b/include/linux/gfp.h
@@ -618,9 +618,9 @@ static inline struct folio *folio_alloc(gfp_t gfp, unsigned int order)
extern unsigned long __get_free_pages(gfp_t gfp_mask, unsigned int order);
extern unsigned long get_zeroed_page(gfp_t gfp_mask);

-void *alloc_pages_exact(size_t size, gfp_t gfp_mask);
+void *alloc_pages_exact(size_t size, gfp_t gfp_mask) __alloc_size(1);
void free_pages_exact(void *virt, size_t size);
-void * __meminit alloc_pages_exact_nid(int nid, size_t size, gfp_t gfp_mask);
+void * __meminit alloc_pages_exact_nid(int nid, size_t size, gfp_t gfp_mask) __alloc_size(1);

#define __get_free_page(gfp_mask) \
__get_free_pages((gfp_mask), 0)