diff options
| author | Gustavo A. R. Silva <gustavoars@kernel.org> | 2025-05-01 18:44:43 -0600 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2025-06-19 15:31:38 +0200 |
| commit | e55f46a11ba55f8614fe54b81c45719d41719ba7 (patch) | |
| tree | 7271ea8894ca1eece1cdcdc0ed71c560a3956929 | |
| parent | b3cfc1f9f58435c43bd14aefd4d51b0cdb29ece2 (diff) | |
overflow: Fix direct struct member initialization in _DEFINE_FLEX()
[ 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>
| -rw-r--r-- | include/linux/overflow.h | 6 |
1 files changed, 3 insertions, 3 deletions
diff --git a/include/linux/overflow.h b/include/linux/overflow.h index 0c7e3dcfe867..823a53cd9a19 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 */ |