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overflow: Allow non-type arg to type_max() and type_min()

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A common use of type_max() is to find the max for the type of a
variable. Using the pattern type_max(typeof(var)) is needlessly
verbose. Instead, since typeof(type) == type we can just explicitly
call typeof() on the argument to type_max() and type_min(). Add
wrappers for readability.

We can do some replacements right away:

$ git grep '\btype_\(min\|max\)(typeof' | wc -l
11

Link: https://lore.kernel.org/r/20240301062221.work.840-kees@kernel.org
Signed-off-by: Kees Cook <keescook@chromium.org>
This commit is contained in:
Kees Cook 2024-02-29 22:22:26 -08:00
parent e606e4b717
commit bd1ebf2467
1 changed files with 7 additions and 5 deletions
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12
include/linux/overflow.h
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@ -31,8 +31,10 @@
* credit to Christian Biere.
*/
#define __type_half_max(type) ((type)1 << (8*sizeof(type) - 1 - is_signed_type(type)))
#define type_max(T) ((T)((__type_half_max(T) - 1) + __type_half_max(T)))
#define type_min(T) ((T)((T)-type_max(T)-(T)1))
#define __type_max(T) ((T)((__type_half_max(T) - 1) + __type_half_max(T)))
#define type_max(t) __type_max(typeof(t))
#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,
@ -207,10 +209,10 @@ static inline bool __must_check __must_check_overflow(bool overflow)
#define __overflows_type_constexpr(x, T) ( \
is_unsigned_type(typeof(x)) ? \
(x) > type_max(typeof(T)) : \
(x) > type_max(T) : \
is_unsigned_type(typeof(T)) ? \
(x) < 0 || (x) > type_max(typeof(T)) : \
(x) < type_min(typeof(T)) || (x) > type_max(typeof(T)))
(x) < 0 || (x) > type_max(T) : \
(x) < type_min(T) || (x) > type_max(T))
#define __overflows_type(x, T) ({ \
typeof(T) v = 0; \