diff options
Diffstat (limited to 'package/kernel/mac80211')
| -rw-r--r-- | package/kernel/mac80211/patches/011-backport-overflow_h.patch | 322 |
1 files changed, 322 insertions, 0 deletions
diff --git a/package/kernel/mac80211/patches/011-backport-overflow_h.patch b/package/kernel/mac80211/patches/011-backport-overflow_h.patch new file mode 100644 index 0000000000..169d3bab15 --- /dev/null +++ b/package/kernel/mac80211/patches/011-backport-overflow_h.patch @@ -0,0 +1,322 @@ +--- a/backport-include/linux/slab.h ++++ b/backport-include/linux/slab.h +@@ -1,6 +1,7 @@ + #ifndef __BACKPORT_SLAB_H + #define __BACKPORT_SLAB_H + #include_next <linux/slab.h> ++#include <linux/overflow.h> + #include <linux/version.h> + + #if LINUX_VERSION_IS_LESS(3,4,0) +--- /dev/null ++++ b/include/linux/overflow.h +@@ -0,0 +1,309 @@ ++/* SPDX-License-Identifier: GPL-2.0 OR MIT */ ++#ifndef __LINUX_OVERFLOW_H ++#define __LINUX_OVERFLOW_H ++ ++#include <linux/compiler.h> ++ ++/* ++ * In the fallback code below, we need to compute the minimum and ++ * maximum values representable in a given type. These macros may also ++ * be useful elsewhere, so we provide them outside the ++ * COMPILER_HAS_GENERIC_BUILTIN_OVERFLOW block. ++ * ++ * It would seem more obvious to do something like ++ * ++ * #define type_min(T) (T)(is_signed_type(T) ? (T)1 << (8*sizeof(T)-1) : 0) ++ * #define type_max(T) (T)(is_signed_type(T) ? ((T)1 << (8*sizeof(T)-1)) - 1 : ~(T)0) ++ * ++ * Unfortunately, the middle expressions, strictly speaking, have ++ * undefined behaviour, and at least some versions of gcc warn about ++ * the type_max expression (but not if -fsanitize=undefined is in ++ * effect; in that case, the warning is deferred to runtime...). ++ * ++ * The slightly excessive casting in type_min is to make sure the ++ * macros also produce sensible values for the exotic type _Bool. [The ++ * overflow checkers only almost work for _Bool, but that's ++ * a-feature-not-a-bug, since people shouldn't be doing arithmetic on ++ * _Bools. Besides, the gcc builtins don't allow _Bool* as third ++ * argument.] ++ * ++ * Idea stolen from ++ * https://mail-index.netbsd.org/tech-misc/2007/02/05/0000.html - ++ * credit to Christian Biere. ++ */ ++#define is_signed_type(type) (((type)(-1)) < (type)1) ++#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)) ++ ++ ++#ifdef COMPILER_HAS_GENERIC_BUILTIN_OVERFLOW ++/* ++ * For simplicity and code hygiene, the fallback code below insists on ++ * a, b and *d having the same type (similar to the min() and max() ++ * macros), whereas gcc's type-generic overflow checkers accept ++ * different types. Hence we don't just make check_add_overflow an ++ * alias for __builtin_add_overflow, but add type checks similar to ++ * below. ++ */ ++#define check_add_overflow(a, b, d) ({ \ ++ typeof(a) __a = (a); \ ++ typeof(b) __b = (b); \ ++ typeof(d) __d = (d); \ ++ (void) (&__a == &__b); \ ++ (void) (&__a == __d); \ ++ __builtin_add_overflow(__a, __b, __d); \ ++}) ++ ++#define check_sub_overflow(a, b, d) ({ \ ++ typeof(a) __a = (a); \ ++ typeof(b) __b = (b); \ ++ typeof(d) __d = (d); \ ++ (void) (&__a == &__b); \ ++ (void) (&__a == __d); \ ++ __builtin_sub_overflow(__a, __b, __d); \ ++}) ++ ++#define check_mul_overflow(a, b, d) ({ \ ++ typeof(a) __a = (a); \ ++ typeof(b) __b = (b); \ ++ typeof(d) __d = (d); \ ++ (void) (&__a == &__b); \ ++ (void) (&__a == __d); \ ++ __builtin_mul_overflow(__a, __b, __d); \ ++}) ++ ++#else ++ ++ ++/* Checking for unsigned overflow is relatively easy without causing UB. */ ++#define __unsigned_add_overflow(a, b, d) ({ \ ++ typeof(a) __a = (a); \ ++ typeof(b) __b = (b); \ ++ typeof(d) __d = (d); \ ++ (void) (&__a == &__b); \ ++ (void) (&__a == __d); \ ++ *__d = __a + __b; \ ++ *__d < __a; \ ++}) ++#define __unsigned_sub_overflow(a, b, d) ({ \ ++ typeof(a) __a = (a); \ ++ typeof(b) __b = (b); \ ++ typeof(d) __d = (d); \ ++ (void) (&__a == &__b); \ ++ (void) (&__a == __d); \ ++ *__d = __a - __b; \ ++ __a < __b; \ ++}) ++/* ++ * If one of a or b is a compile-time constant, this avoids a division. ++ */ ++#define __unsigned_mul_overflow(a, b, d) ({ \ ++ typeof(a) __a = (a); \ ++ typeof(b) __b = (b); \ ++ typeof(d) __d = (d); \ ++ (void) (&__a == &__b); \ ++ (void) (&__a == __d); \ ++ *__d = __a * __b; \ ++ __builtin_constant_p(__b) ? \ ++ __b > 0 && __a > type_max(typeof(__a)) / __b : \ ++ __a > 0 && __b > type_max(typeof(__b)) / __a; \ ++}) ++ ++/* ++ * For signed types, detecting overflow is much harder, especially if ++ * we want to avoid UB. But the interface of these macros is such that ++ * we must provide a result in *d, and in fact we must produce the ++ * result promised by gcc's builtins, which is simply the possibly ++ * wrapped-around value. Fortunately, we can just formally do the ++ * operations in the widest relevant unsigned type (u64) and then ++ * truncate the result - gcc is smart enough to generate the same code ++ * with and without the (u64) casts. ++ */ ++ ++/* ++ * Adding two signed integers can overflow only if they have the same ++ * sign, and overflow has happened iff the result has the opposite ++ * sign. ++ */ ++#define __signed_add_overflow(a, b, d) ({ \ ++ typeof(a) __a = (a); \ ++ typeof(b) __b = (b); \ ++ typeof(d) __d = (d); \ ++ (void) (&__a == &__b); \ ++ (void) (&__a == __d); \ ++ *__d = (u64)__a + (u64)__b; \ ++ (((~(__a ^ __b)) & (*__d ^ __a)) \ ++ & type_min(typeof(__a))) != 0; \ ++}) ++ ++/* ++ * Subtraction is similar, except that overflow can now happen only ++ * when the signs are opposite. In this case, overflow has happened if ++ * the result has the opposite sign of a. ++ */ ++#define __signed_sub_overflow(a, b, d) ({ \ ++ typeof(a) __a = (a); \ ++ typeof(b) __b = (b); \ ++ typeof(d) __d = (d); \ ++ (void) (&__a == &__b); \ ++ (void) (&__a == __d); \ ++ *__d = (u64)__a - (u64)__b; \ ++ ((((__a ^ __b)) & (*__d ^ __a)) \ ++ & type_min(typeof(__a))) != 0; \ ++}) ++ ++/* ++ * Signed multiplication is rather hard. gcc always follows C99, so ++ * division is truncated towards 0. This means that we can write the ++ * overflow check like this: ++ * ++ * (a > 0 && (b > MAX/a || b < MIN/a)) || ++ * (a < -1 && (b > MIN/a || b < MAX/a) || ++ * (a == -1 && b == MIN) ++ * ++ * The redundant casts of -1 are to silence an annoying -Wtype-limits ++ * (included in -Wextra) warning: When the type is u8 or u16, the ++ * __b_c_e in check_mul_overflow obviously selects ++ * __unsigned_mul_overflow, but unfortunately gcc still parses this ++ * code and warns about the limited range of __b. ++ */ ++ ++#define __signed_mul_overflow(a, b, d) ({ \ ++ typeof(a) __a = (a); \ ++ typeof(b) __b = (b); \ ++ typeof(d) __d = (d); \ ++ typeof(a) __tmax = type_max(typeof(a)); \ ++ typeof(a) __tmin = type_min(typeof(a)); \ ++ (void) (&__a == &__b); \ ++ (void) (&__a == __d); \ ++ *__d = (u64)__a * (u64)__b; \ ++ (__b > 0 && (__a > __tmax/__b || __a < __tmin/__b)) || \ ++ (__b < (typeof(__b))-1 && (__a > __tmin/__b || __a < __tmax/__b)) || \ ++ (__b == (typeof(__b))-1 && __a == __tmin); \ ++}) ++ ++ ++#define check_add_overflow(a, b, d) \ ++ __builtin_choose_expr(is_signed_type(typeof(a)), \ ++ __signed_add_overflow(a, b, d), \ ++ __unsigned_add_overflow(a, b, d)) ++ ++#define check_sub_overflow(a, b, d) \ ++ __builtin_choose_expr(is_signed_type(typeof(a)), \ ++ __signed_sub_overflow(a, b, d), \ ++ __unsigned_sub_overflow(a, b, d)) ++ ++#define check_mul_overflow(a, b, d) \ ++ __builtin_choose_expr(is_signed_type(typeof(a)), \ ++ __signed_mul_overflow(a, b, d), \ ++ __unsigned_mul_overflow(a, b, d)) ++ ++ ++#endif /* COMPILER_HAS_GENERIC_BUILTIN_OVERFLOW */ ++ ++/** check_shl_overflow() - Calculate a left-shifted value and check overflow ++ * ++ * @a: Value to be shifted ++ * @s: How many bits left to shift ++ * @d: Pointer to where to store the result ++ * ++ * Computes *@d = (@a << @s) ++ * ++ * Returns true if '*d' cannot hold the result or when 'a << s' doesn't ++ * make sense. Example conditions: ++ * - 'a << s' causes bits to be lost when stored in *d. ++ * - 's' is garbage (e.g. negative) or so large that the result of ++ * 'a << s' is guaranteed to be 0. ++ * - 'a' is negative. ++ * - 'a << s' sets the sign bit, if any, in '*d'. ++ * ++ * '*d' will hold the results of the attempted shift, but is not ++ * considered "safe for use" if false is returned. ++ */ ++#define check_shl_overflow(a, s, d) ({ \ ++ typeof(a) _a = a; \ ++ typeof(s) _s = s; \ ++ typeof(d) _d = d; \ ++ u64 _a_full = _a; \ ++ unsigned int _to_shift = \ ++ _s >= 0 && _s < 8 * sizeof(*d) ? _s : 0; \ ++ *_d = (_a_full << _to_shift); \ ++ (_to_shift != _s || *_d < 0 || _a < 0 || \ ++ (*_d >> _to_shift) != _a); \ ++}) ++ ++/** ++ * array_size() - Calculate size of 2-dimensional array. ++ * ++ * @a: dimension one ++ * @b: dimension two ++ * ++ * Calculates size of 2-dimensional array: @a * @b. ++ * ++ * Returns: number of bytes needed to represent the array or SIZE_MAX on ++ * overflow. ++ */ ++static inline __must_check size_t array_size(size_t a, size_t b) ++{ ++ size_t bytes; ++ ++ if (check_mul_overflow(a, b, &bytes)) ++ return SIZE_MAX; ++ ++ return bytes; ++} ++ ++/** ++ * array3_size() - Calculate size of 3-dimensional array. ++ * ++ * @a: dimension one ++ * @b: dimension two ++ * @c: dimension three ++ * ++ * Calculates size of 3-dimensional array: @a * @b * @c. ++ * ++ * Returns: number of bytes needed to represent the array or SIZE_MAX on ++ * overflow. ++ */ ++static inline __must_check size_t array3_size(size_t a, size_t b, size_t c) ++{ ++ size_t bytes; ++ ++ if (check_mul_overflow(a, b, &bytes)) ++ return SIZE_MAX; ++ if (check_mul_overflow(bytes, c, &bytes)) ++ return SIZE_MAX; ++ ++ return bytes; ++} ++ ++static inline __must_check size_t __ab_c_size(size_t n, size_t size, size_t c) ++{ ++ size_t bytes; ++ ++ if (check_mul_overflow(n, size, &bytes)) ++ return SIZE_MAX; ++ if (check_add_overflow(bytes, c, &bytes)) ++ return SIZE_MAX; ++ ++ return bytes; ++} ++ ++/** ++ * struct_size() - Calculate size of structure with trailing array. ++ * @p: Pointer to the structure. ++ * @member: Name of the array member. ++ * @n: Number of elements in the array. ++ * ++ * Calculates size of memory needed for structure @p followed by an ++ * array of @n @member elements. ++ * ++ * Return: number of bytes needed or SIZE_MAX on overflow. ++ */ ++#define struct_size(p, member, n) \ ++ __ab_c_size(n, \ ++ sizeof(*(p)->member) + __must_be_array((p)->member),\ ++ sizeof(*(p))) ++ ++#endif /* __LINUX_OVERFLOW_H */ |