Address sanitization

include/mem/asan.h

• void asan_init(void)
• void asan_poison(void *addr,size_t size)
• void asan_unpoison(void *addr,size_t size)

Defines

• ASAN_SHADOW_SCALE: 3ULL /* 1 shadow byte per 8 real bytes */
• ASAN_SHADOW_OFFSET: 0xfffffc0000000000ULL /* fixed virtual base for shadow memory */
• ASAN_REDZONE: 16 /* optional redzone per allocation */
• ASAN_POISON_VALUE: 0xFF

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