Commit 9a930484 authored by Kees Cook's avatar Kees Cook
Browse files

overflow: Clarify expectations for getting DEFINE_FLEX variable sizes 



Mention the use of __member_size() for DEFINE_FLEX variables as a hint
for getting at the compile-time size of the resulting flexible array
member.

Reviewed-by: default avatarGustavo A. R. Silva <gustavoars@kernel.org>
Link: https://lore.kernel.org/r/20250416172911.work.854-kees@kernel.org


Signed-off-by: default avatarKees Cook <kees@kernel.org>
parent a510c186

include/linux/overflow.h

+2 −0
Original line number Diff line number Diff line
@@ -419,6 +419,7 @@ static inline size_t __must_check size_sub(size_t minuend, size_t subtrahend) 
 * Define a zeroed, on-stack, instance of @type structure with a trailing

 * flexible array member.

 * Use __struct_size(@name) to get compile-time size of it afterwards.

 * Use __member_size(@name->member) to get compile-time size of @name members.

 */

#define DEFINE_RAW_FLEX(type, name, member, count)	\

	_DEFINE_FLEX(type, name, member, count, = {})
@@ -436,6 +437,7 @@ static inline size_t __must_check size_sub(size_t minuend, size_t subtrahend) 
 * Define a zeroed, on-stack, instance of @TYPE structure with a trailing

 * flexible array member.

 * Use __struct_size(@NAME) to get compile-time size of it afterwards.

 * Use __member_size(@NAME->member) to get compile-time size of @NAME members.

 */

#define DEFINE_FLEX(TYPE, NAME, MEMBER, COUNTER, COUNT)	\

	_DEFINE_FLEX(TYPE, NAME, MEMBER, COUNT, = { .obj.COUNTER = COUNT, })