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3e6aa687d9
The code used in the header was taken from linux kernel commit f0907827a8a9152aedac2833ed1b674a7b2a44f2. Rasmus Villemoes <linux@rasmusvillemoes.dk>, the original author of the patch, was contacted directly, confirmed his authorship of the code, and gave his permission on treating that dual license as MIT and including into GRUB2 sources Signed-off-by: Alex Burmashev <alexander.burmashev@oracle.com> Patch-Name: safe-alloc-5.patch
155 lines
5.3 KiB
C
155 lines
5.3 KiB
C
/*
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* GRUB -- GRand Unified Bootloader
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* Copyright (C) 2020 Free Software Foundation, Inc.
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*
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* GRUB is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* GRUB is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with GRUB. If not, see <http://www.gnu.org/licenses/>.
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*
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* Arithmetic operations that protect against overflow.
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*/
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#ifndef GRUB_SAFEMATH_H
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#define GRUB_SAFEMATH_H 1
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#include <grub/compiler.h>
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/* These appear in gcc 5.1 and clang 3.8. */
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#if GNUC_PREREQ(5, 1) || CLANG_PREREQ(3, 8)
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#define grub_add(a, b, res) __builtin_add_overflow(a, b, res)
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#define grub_sub(a, b, res) __builtin_sub_overflow(a, b, res)
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#define grub_mul(a, b, res) __builtin_mul_overflow(a, b, res)
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#else
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/*
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* Copyright 2020 Rasmus Villemoes
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy
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* of this software and associated documentation files (the "Software"), to
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* deal in the Software without restriction, including without limitation the
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* rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
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* sell copies of the Software, and to permit persons to whom the Software is
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* furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in
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* all copies or substantial portions of the Software.
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
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* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
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* IN THE SOFTWARE.
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*/
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/*
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* The code used in this header was taken from linux kernel commit
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* f0907827a8a9152aedac2833ed1b674a7b2a44f2
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* Rasmus Villemoes <linux@rasmusvillemoes.dk>, the original author of the
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* patch, was contacted directly, confirmed his authorship of the code, and
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* gave his permission on treating that dual license as MIT and including into
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* GRUB2 sources
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*/
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#include <grub/types.h>
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#define is_signed_type(type) (((type)(-1)) < (type)1)
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#define __type_half_max(type) ((type)1 << (8*sizeof(type) - 1 - is_signed_type(type)))
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#define type_max(T) ((T)((__type_half_max(T) - 1) + __type_half_max(T)))
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#define type_min(T) ((T)((T)-type_max(T)-(T)1))
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#define __unsigned_add_overflow(a, b, d) ({ \
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typeof(+(a)) __a = (a); \
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typeof(+(b)) __b = (b); \
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typeof(d) __d = (d); \
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(void) (&__a == &__b); \
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(void) (&__a == __d); \
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*__d = __a + __b; \
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*__d < __a; \
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})
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#define __unsigned_sub_overflow(a, b, d) ({ \
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typeof(+(a)) __a = (a); \
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typeof(+(b)) __b = (b); \
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typeof(d) __d = (d); \
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(void) (&__a == &__b); \
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(void) (&__a == __d); \
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*__d = __a - __b; \
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__a < __b; \
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})
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#define __unsigned_mul_overflow(a, b, d) ({ \
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typeof(+(a)) __a = (a); \
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typeof(+(b)) __b = (b); \
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typeof(d) __d = (d); \
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(void) (&__a == &__b); \
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(void) (&__a == __d); \
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*__d = __a * __b; \
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__builtin_constant_p(__b) ? \
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__b > 0 && __a > type_max(typeof(__a)) / __b :\
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__a > 0 && __b > type_max(typeof(__b)) / __a; \
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})
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#define __signed_add_overflow(a, b, d) ({ \
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typeof(+(a)) __a = (a); \
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typeof(+(b)) __b = (b); \
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typeof(d) __d = (d); \
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(void) (&__a == &__b); \
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(void) (&__a == __d); \
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*__d = (grub_uint64_t)__a + (grub_uint64_t)__b; \
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(((~(__a ^ __b)) & (*__d ^ __a)) \
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& type_min(typeof(__a))) != 0; \
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})
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#define __signed_sub_overflow(a, b, d) ({ \
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typeof(+(a)) __a = (a); \
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typeof(+(b)) __b = (b); \
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typeof(d) __d = (d); \
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(void) (&__a == &__b); \
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(void) (&__a == __d); \
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*__d = (grub_uint64_t)__a - (grub_uint64_t)__b; \
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((((__a ^ __b)) & (*__d ^ __a)) \
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& type_min(typeof(__a))) != 0; \
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})
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#define __signed_mul_overflow(a, b, d) ({ \
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typeof(+(a)) __a = (a); \
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typeof(+(b)) __b = (b); \
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typeof(d) __d = (d); \
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typeof(+(a)) __tmax = type_max(typeof(+(a))); \
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typeof(+(a)) __tmin = type_min(typeof(+(a))); \
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(void) (&__a == &__b); \
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(void) (&__a == __d); \
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*__d = (grub_uint64_t)__a * (grub_uint64_t)__b; \
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(__b > 0 && (__a > __tmax/__b || __a < __tmin/__b)) ||\
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(__b < (typeof(__b))-1 && \
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(__a > __tmin/__b || __a < __tmax/__b)) || \
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(__b == (typeof(__b))-1 && __a == __tmin); \
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})
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#define grub_add(a, b, d) \
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__builtin_choose_expr(is_signed_type(typeof(+(a))), \
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__signed_add_overflow(a, b, d), \
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__unsigned_add_overflow(a, b, d))
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#define grub_sub(a, b, d) \
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__builtin_choose_expr(is_signed_type(typeof(+(a))), \
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__signed_sub_overflow(a, b, d), \
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__unsigned_sub_overflow(a, b, d))
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#define grub_mul(a, b, d) \
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__builtin_choose_expr(is_signed_type(typeof(+(a))), \
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__signed_mul_overflow(a, b, d), \
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__unsigned_mul_overflow(a, b, d))
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#endif
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#endif /* GRUB_SAFEMATH_H */
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