forked from mirrors/linux
overflow: add DEFINE_FLEX() for on-stack allocs
Add DEFINE_FLEX() macro for on-stack allocations of structs with
flexible array member.
Expose __struct_size() macro outside of fortify-string.h, as it could be
used to read size of structs allocated by DEFINE_FLEX().
Move __member_size() alongside it.
-Kees
Using underlying array for on-stack storage lets us to declare
known-at-compile-time structures without kzalloc().
Actual usage for ice driver is in following patches of the series.
Missing __has_builtin() workaround is moved up to serve also assembly
compilation with m68k-linux-gcc, see [1].
Error was (note the .S file extension):
In file included from ../include/linux/linkage.h:5,
from ../arch/m68k/fpsp040/skeleton.S:40:
../include/linux/compiler_types.h:331:5: warning: "__has_builtin" is not defined, evaluates to 0 [-Wundef]
331 | #if __has_builtin(__builtin_dynamic_object_size)
| ^~~~~~~~~~~~~
../include/linux/compiler_types.h:331:18: error: missing binary operator before token "("
331 | #if __has_builtin(__builtin_dynamic_object_size)
| ^
[1] https://lore.kernel.org/netdev/202308112122.OuF0YZqL-lkp@intel.com/
Co-developed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Przemek Kitszel <przemyslaw.kitszel@intel.com>
Link: https://lore.kernel.org/r/20230912115937.1645707-2-przemyslaw.kitszel@intel.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Przemek Kitszel
Jakub Kicinski
parent
e643597346
commit
26dd68d293
3 changed files with 56 additions and 15 deletions
|
|
@ -2,6 +2,15 @@
|
|||
#ifndef __LINUX_COMPILER_TYPES_H
|
||||
#define __LINUX_COMPILER_TYPES_H
|
||||
|
||||
/*
|
||||
* __has_builtin is supported on gcc >= 10, clang >= 3 and icc >= 21.
|
||||
* In the meantime, to support gcc < 10, we implement __has_builtin
|
||||
* by hand.
|
||||
*/
|
||||
#ifndef __has_builtin
|
||||
#define __has_builtin(x) (0)
|
||||
#endif
|
||||
|
||||
#ifndef __ASSEMBLY__
|
||||
|
||||
/*
|
||||
|
|
@ -134,17 +143,6 @@ static inline void __chk_io_ptr(const volatile void __iomem *ptr) { }
|
|||
# define __preserve_most
|
||||
#endif
|
||||
|
||||
/* Builtins */
|
||||
|
||||
/*
|
||||
* __has_builtin is supported on gcc >= 10, clang >= 3 and icc >= 21.
|
||||
* In the meantime, to support gcc < 10, we implement __has_builtin
|
||||
* by hand.
|
||||
*/
|
||||
#ifndef __has_builtin
|
||||
#define __has_builtin(x) (0)
|
||||
#endif
|
||||
|
||||
/* Compiler specific macros. */
|
||||
#ifdef __clang__
|
||||
#include <linux/compiler-clang.h>
|
||||
|
|
@ -352,6 +350,18 @@ struct ftrace_likely_data {
|
|||
# define __realloc_size(x, ...)
|
||||
#endif
|
||||
|
||||
/*
|
||||
* When the size of an allocated object is needed, use the best available
|
||||
* mechanism to find it. (For cases where sizeof() cannot be used.)
|
||||
*/
|
||||
#if __has_builtin(__builtin_dynamic_object_size)
|
||||
#define __struct_size(p) __builtin_dynamic_object_size(p, 0)
|
||||
#define __member_size(p) __builtin_dynamic_object_size(p, 1)
|
||||
#else
|
||||
#define __struct_size(p) __builtin_object_size(p, 0)
|
||||
#define __member_size(p) __builtin_object_size(p, 1)
|
||||
#endif
|
||||
|
||||
#ifndef asm_volatile_goto
|
||||
#define asm_volatile_goto(x...) asm goto(x)
|
||||
#endif
|
||||
|
|
|
|||
|
|
@ -93,13 +93,9 @@ extern char *__underlying_strncpy(char *p, const char *q, __kernel_size_t size)
|
|||
#if __has_builtin(__builtin_dynamic_object_size)
|
||||
#define POS __pass_dynamic_object_size(1)
|
||||
#define POS0 __pass_dynamic_object_size(0)
|
||||
#define __struct_size(p) __builtin_dynamic_object_size(p, 0)
|
||||
#define __member_size(p) __builtin_dynamic_object_size(p, 1)
|
||||
#else
|
||||
#define POS __pass_object_size(1)
|
||||
#define POS0 __pass_object_size(0)
|
||||
#define __struct_size(p) __builtin_object_size(p, 0)
|
||||
#define __member_size(p) __builtin_object_size(p, 1)
|
||||
#endif
|
||||
|
||||
#define __compiletime_lessthan(bounds, length) ( \
|
||||
|
|
|
|||
|
|
@ -309,4 +309,39 @@ static inline size_t __must_check size_sub(size_t minuend, size_t subtrahend)
|
|||
#define struct_size_t(type, member, count) \
|
||||
struct_size((type *)NULL, member, count)
|
||||
|
||||
/**
|
||||
* _DEFINE_FLEX() - helper macro for DEFINE_FLEX() family.
|
||||
* Enables caller macro to pass (different) initializer.
|
||||
*
|
||||
* @type: structure type name, including "struct" keyword.
|
||||
* @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).
|
||||
*/
|
||||
#define _DEFINE_FLEX(type, name, member, count, initializer) \
|
||||
_Static_assert(__builtin_constant_p(count), \
|
||||
"onstack flex array members require compile-time const count"); \
|
||||
union { \
|
||||
u8 bytes[struct_size_t(type, member, count)]; \
|
||||
type obj; \
|
||||
} name##_u initializer; \
|
||||
type *name = (type *)&name##_u
|
||||
|
||||
/**
|
||||
* DEFINE_FLEX() - Define an on-stack instance of structure with a trailing
|
||||
* flexible array member.
|
||||
*
|
||||
* @type: structure type name, including "struct" keyword.
|
||||
* @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.
|
||||
*
|
||||
* 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.
|
||||
*/
|
||||
#define DEFINE_FLEX(type, name, member, count) \
|
||||
_DEFINE_FLEX(type, name, member, count, = {})
|
||||
|
||||
#endif /* __LINUX_OVERFLOW_H */
|
||||
|
|
|
|||
Loading…
Reference in a new issue