jmb/hardened_malloc
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Merge 10e27e2142 into e371736b17

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Thor Preimesberger 2025-09-23 18:25:00 -04:00 • committed by GitHub
commit ed604aa2d1
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1 changed files with 15 additions and 1 deletions
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16
h_malloc.c
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@ -20,6 +20,13 @@
#include "random.h"
#include "util.h"
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wundef"
#if __x86_64__
#include "immintrin.h"
#endif
#pragma GCC diagnostic pop
#ifdef USE_PKEY
#include <sys/mman.h>
#endif
@ -405,8 +412,15 @@ static size_t get_free_slot(struct random_state *rng, size_t slots, const struct
// randomize start location for linear search (uniform random choice is too slow)
size_t random_index = get_random_u16_uniform(rng, slots);
size_t first_bitmap = random_index / U64_WIDTH;
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wundef"
// __BMI2__ is idiomatic to gcc unfortunately.
#if __x86_64__ && (__BMI2__ || (__clang__ && __BMI2INTRIN_H_))
#pragma GCC diagnostic pop
u64 random_split = ~(~0UL << _pext_u64(random_index, 8));
#else
u64 random_split = ~(~0UL << (random_index - first_bitmap * U64_WIDTH));
#endif
size_t i = first_bitmap;
u64 masked = metadata->bitmap[i];
masked |= random_split;