diff options
Diffstat (limited to 'include/linux/overflow.h')
| -rw-r--r-- | include/linux/overflow.h | 186 |
1 files changed, 167 insertions, 19 deletions
diff --git a/include/linux/overflow.h b/include/linux/overflow.h index 0c7e3dcfe867..a8cb6319b4fb 100644 --- a/include/linux/overflow.h +++ b/include/linux/overflow.h @@ -36,19 +36,13 @@ #define __type_min(T) ((T)((T)-type_max(T)-(T)1)) #define type_min(t) __type_min(typeof(t)) -/* - * Avoids triggering -Wtype-limits compilation warning, - * while using unsigned data types to check a < 0. - */ -#define is_non_negative(a) ((a) > 0 || (a) == 0) -#define is_negative(a) (!(is_non_negative(a))) /* * Allows for effectively applying __must_check to a macro so we can have * both the type-agnostic benefits of the macros while also being able to * enforce that the return value is, in fact, checked. */ -static inline bool __must_check __must_check_overflow(bool overflow) +static __always_inline bool __must_check __must_check_overflow(bool overflow) { return unlikely(overflow); } @@ -201,9 +195,9 @@ static inline bool __must_check __must_check_overflow(bool overflow) typeof(d) _d = d; \ unsigned long long _a_full = _a; \ unsigned int _to_shift = \ - is_non_negative(_s) && _s < 8 * sizeof(*d) ? _s : 0; \ + _s >= 0 && _s < 8 * sizeof(*d) ? _s : 0; \ *_d = (_a_full << _to_shift); \ - (_to_shift != _s || is_negative(*_d) || is_negative(_a) || \ + (_to_shift != _s || *_d < 0 || _a < 0 || \ (*_d >> _to_shift) != _a); \ })) @@ -239,6 +233,76 @@ static inline bool __must_check __must_check_overflow(bool overflow) __overflows_type(n, T)) /** + * range_overflows() - Check if a range is out of bounds + * @start: Start of the range. + * @size: Size of the range. + * @max: Exclusive upper boundary. + * + * A strict check to determine if the range [@start, @start + @size) is + * invalid with respect to the allowable range [0, @max). Any range + * starting at or beyond @max is considered an overflow, even if @size is 0. + * + * Returns: true if the range is out of bounds. + */ +#define range_overflows(start, size, max) ({ \ + typeof(start) start__ = (start); \ + typeof(size) size__ = (size); \ + typeof(max) max__ = (max); \ + (void)(&start__ == &size__); \ + (void)(&start__ == &max__); \ + start__ >= max__ || size__ > max__ - start__; \ +}) + +/** + * range_overflows_t() - Check if a range is out of bounds + * @type: Data type to use. + * @start: Start of the range. + * @size: Size of the range. + * @max: Exclusive upper boundary. + * + * Same as range_overflows() but forcing the parameters to @type. + * + * Returns: true if the range is out of bounds. + */ +#define range_overflows_t(type, start, size, max) \ + range_overflows((type)(start), (type)(size), (type)(max)) + +/** + * range_end_overflows() - Check if a range's endpoint is out of bounds + * @start: Start of the range. + * @size: Size of the range. + * @max: Exclusive upper boundary. + * + * Checks only if the endpoint of a range (@start + @size) exceeds @max. + * Unlike range_overflows(), a zero-sized range at the boundary (@start == @max) + * is not considered an overflow. Useful for iterator-style checks. + * + * Returns: true if the endpoint exceeds the boundary. + */ +#define range_end_overflows(start, size, max) ({ \ + typeof(start) start__ = (start); \ + typeof(size) size__ = (size); \ + typeof(max) max__ = (max); \ + (void)(&start__ == &size__); \ + (void)(&start__ == &max__); \ + start__ > max__ || size__ > max__ - start__; \ +}) + +/** + * range_end_overflows_t() - Check if a range's endpoint is out of bounds + * @type: Data type to use. + * @start: Start of the range. + * @size: Size of the range. + * @max: Exclusive upper boundary. + * + * Same as range_end_overflows() but forcing the parameters to @type. + * + * Returns: true if the endpoint exceeds the boundary. + */ +#define range_end_overflows_t(type, start, size, max) \ + range_end_overflows((type)(start), (type)(size), (type)(max)) + +/** * castable_to_type - like __same_type(), but also allows for casted literals * * @n: variable or constant value @@ -263,7 +327,7 @@ static inline bool __must_check __must_check_overflow(bool overflow) * with any overflow causing the return value to be SIZE_MAX. The * lvalue must be size_t to avoid implicit type conversion. */ -static inline size_t __must_check size_mul(size_t factor1, size_t factor2) +static __always_inline size_t __must_check size_mul(size_t factor1, size_t factor2) { size_t bytes; @@ -282,7 +346,7 @@ static inline size_t __must_check size_mul(size_t factor1, size_t factor2) * with any overflow causing the return value to be SIZE_MAX. The * lvalue must be size_t to avoid implicit type conversion. */ -static inline size_t __must_check size_add(size_t addend1, size_t addend2) +static __always_inline size_t __must_check size_add(size_t addend1, size_t addend2) { size_t bytes; @@ -303,7 +367,7 @@ static inline size_t __must_check size_add(size_t addend1, size_t addend2) * argument may be SIZE_MAX (or the result with be forced to SIZE_MAX). * The lvalue must be size_t to avoid implicit type conversion. */ -static inline size_t __must_check size_sub(size_t minuend, size_t subtrahend) +static __always_inline size_t __must_check size_sub(size_t minuend, size_t subtrahend) { size_t bytes; @@ -389,25 +453,50 @@ static inline size_t __must_check size_sub(size_t minuend, size_t subtrahend) struct_size((type *)NULL, member, count) /** - * _DEFINE_FLEX() - helper macro for DEFINE_FLEX() family. - * Enables caller macro to pass (different) initializer. + * struct_offset() - Calculate the offset of a member within a struct + * @p: Pointer to the struct + * @member: Name of the member to get the offset of + * + * Calculates the offset of a particular @member of the structure pointed + * to by @p. + * + * Return: number of bytes to the location of @member. + */ +#define struct_offset(p, member) (offsetof(typeof(*(p)), member)) + +/** + * __DEFINE_FLEX() - helper macro for DEFINE_FLEX() family. + * Enables caller macro to pass arbitrary trailing expressions * * @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). + * @trailer: Trailing expressions for attributes and/or initializers. */ -#define _DEFINE_FLEX(type, name, member, count, initializer...) \ +#define __DEFINE_FLEX(type, name, member, count, trailer...) \ _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; \ + } name##_u trailer; \ type *name = (type *)&name##_u /** + * _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 (e.g., pass `= { }` at minimum). + */ +#define _DEFINE_FLEX(type, name, member, count, initializer...) \ + __DEFINE_FLEX(type, name, member, count, = { .obj initializer }) + +/** * DEFINE_RAW_FLEX() - Define an on-stack instance of structure with a trailing * flexible array member, when it does not have a __counted_by annotation. * @@ -419,9 +508,12 @@ 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. + * Use STACK_FLEX_ARRAY_SIZE(@name, @member) to get compile-time number of + * elements in array @member. */ #define DEFINE_RAW_FLEX(type, name, member, count) \ - _DEFINE_FLEX(type, name, member, count, = {}) + __DEFINE_FLEX(type, name, member, count, = { }) /** * DEFINE_FLEX() - Define an on-stack instance of structure with a trailing @@ -436,8 +528,64 @@ 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. + * Use STACK_FLEX_ARRAY_SIZE(@name, @member) to get compile-time number of + * elements in array @member. */ #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, }) + +/** + * STACK_FLEX_ARRAY_SIZE() - helper macro for DEFINE_FLEX() family. + * Returns the number of elements in @array. + * + * @name: Name for a variable defined in DEFINE_RAW_FLEX()/DEFINE_FLEX(). + * @array: Name of the array member. + */ +#define STACK_FLEX_ARRAY_SIZE(name, array) \ + (__member_size((name)->array) / sizeof(*(name)->array) + \ + __must_be_array((name)->array)) + +/** + * typeof_flex_counter() - Return the type of the counter variable of a given + * flexible array member annotated by __counted_by(). + * @FAM: Instance of flexible array member within a given struct. + * + * Returns: "size_t" if no annotation exists. + */ +#define typeof_flex_counter(FAM) \ + typeof(_Generic(__flex_counter(FAM), \ + void *: (size_t)0, \ + default: *__flex_counter(FAM))) + +/** + * overflows_flex_counter_type() - Check if the counter associated with the + * given flexible array member can represent + * a value. + * @TYPE: Type of the struct that contains the @FAM. + * @FAM: Member name of the FAM within @TYPE. + * @COUNT: Value to check against the __counted_by annotated @FAM's counter. + * + * Returns: true if @COUNT can be represented in the @FAM's counter. When + * @FAM is not annotated with __counted_by(), always returns true. + */ +#define overflows_flex_counter_type(TYPE, FAM, COUNT) \ + (overflows_type(COUNT, typeof_flex_counter(((TYPE *)NULL)->FAM))) + +/** + * __set_flex_counter() - Set the counter associated with the given flexible + * array member that has been annoated by __counted_by(). + * @FAM: Instance of flexible array member within a given struct. + * @COUNT: Value to store to the __counted_by annotated @FAM_PTR's counter. + * + * This is a no-op if no annotation exists. Count needs to be checked with + * overflows_flex_counter_type() before using this function. + */ +#define __set_flex_counter(FAM, COUNT) \ +({ \ + *_Generic(__flex_counter(FAM), \ + void *: &(size_t){ 0 }, \ + default: __flex_counter(FAM)) = (COUNT); \ +}) #endif /* __LINUX_OVERFLOW_H */ |