6.15-stable review patch. If anyone has any objections, please let me know.
------------------
From: Gustavo A. R. Silva gustavoars@kernel.org
[ Upstream commit 47e36ed7840661a9f7fb53554a1b04a5f8daffea ]
Currently, to statically initialize the struct members of the `type` object created by _DEFINE_FLEX(), the internal `obj` member must be explicitly referenced at the call site. See:
struct flex { int a; int b; struct foo flex_array[]; };
_DEFINE_FLEX(struct flex, instance, flex_array, FIXED_SIZE, = { .obj = { .a = 0, .b = 1, }, });
This leaks _DEFINE_FLEX() internal implementation details and make the helper harder to use and read.
Fix this and allow for a more natural and intuitive C99 init-style:
_DEFINE_FLEX(struct flex, instance, flex_array, FIXED_SIZE, = { .a = 0, .b = 1, });
Note that before these changes, the `initializer` argument was optional, but now it's required.
Also, update "counter" member initialization in DEFINE_FLEX().
Fixes: 26dd68d293fd ("overflow: add DEFINE_FLEX() for on-stack allocs") Signed-off-by: Gustavo A. R. Silva gustavoars@kernel.org Link: https://lore.kernel.org/r/aBQVeyKfLOkO9Yss@kspp Signed-off-by: Kees Cook kees@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- include/linux/overflow.h | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/include/linux/overflow.h b/include/linux/overflow.h index 0c7e3dcfe8670..823a53cd9a193 100644 --- a/include/linux/overflow.h +++ b/include/linux/overflow.h @@ -396,7 +396,7 @@ static inline size_t __must_check size_sub(size_t minuend, size_t subtrahend) * @name: Name for a variable to define. * @member: Name of the array member. * @count: Number of elements in the array; must be compile-time const. - * @initializer: initializer expression (could be empty for no init). + * @initializer: Initializer expression (e.g., pass `= { }` at minimum). */ #define _DEFINE_FLEX(type, name, member, count, initializer...) \ _Static_assert(__builtin_constant_p(count), \ @@ -404,7 +404,7 @@ static inline size_t __must_check size_sub(size_t minuend, size_t subtrahend) union { \ u8 bytes[struct_size_t(type, member, count)]; \ type obj; \ - } name##_u initializer; \ + } name##_u = { .obj initializer }; \ type *name = (type *)&name##_u
/** @@ -438,6 +438,6 @@ static inline size_t __must_check size_sub(size_t minuend, size_t subtrahend) * Use __struct_size(@NAME) to get compile-time size of it afterwards. */ #define DEFINE_FLEX(TYPE, NAME, MEMBER, COUNTER, COUNT) \ - _DEFINE_FLEX(TYPE, NAME, MEMBER, COUNT, = { .obj.COUNTER = COUNT, }) + _DEFINE_FLEX(TYPE, NAME, MEMBER, COUNT, = { .COUNTER = COUNT, })
#endif /* __LINUX_OVERFLOW_H */