1 //===-- hwasan_poisoning.cpp ------------------------------------*- C++ -*-===// 2 // 3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 4 // See https://llvm.org/LICENSE.txt for license information. 5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 6 // 7 //===----------------------------------------------------------------------===// 8 // 9 // This file is a part of HWAddressSanitizer. 10 // 11 //===----------------------------------------------------------------------===// 12 13 #include "hwasan_poisoning.h" 14 15 #include "hwasan_mapping.h" 16 #include "interception/interception.h" 17 #include "sanitizer_common/sanitizer_common.h" 18 #include "sanitizer_common/sanitizer_linux.h" 19 20 namespace __hwasan { 21 22 uptr TagMemoryAligned(uptr p, uptr size, tag_t tag) { 23 CHECK(IsAligned(p, kShadowAlignment)); 24 CHECK(IsAligned(size, kShadowAlignment)); 25 uptr shadow_start = MemToShadow(p); 26 uptr shadow_size = MemToShadowSize(size); 27 28 uptr page_size = GetPageSizeCached(); 29 uptr page_start = RoundUpTo(shadow_start, page_size); 30 uptr page_end = RoundDownTo(shadow_start + shadow_size, page_size); 31 uptr threshold = common_flags()->clear_shadow_mmap_threshold; 32 if (SANITIZER_LINUX && 33 UNLIKELY(page_end >= page_start + threshold && tag == 0)) { 34 internal_memset((void *)shadow_start, tag, page_start - shadow_start); 35 internal_memset((void *)page_end, tag, 36 shadow_start + shadow_size - page_end); 37 // For an anonymous private mapping MADV_DONTNEED will return a zero page on 38 // Linux. 39 ReleaseMemoryPagesToOSAndZeroFill(page_start, page_end); 40 } else { 41 internal_memset((void *)shadow_start, tag, shadow_size); 42 } 43 return AddTagToPointer(p, tag); 44 } 45 46 uptr TagMemory(uptr p, uptr size, tag_t tag) { 47 uptr start = RoundDownTo(p, kShadowAlignment); 48 uptr end = RoundUpTo(p + size, kShadowAlignment); 49 return TagMemoryAligned(start, end - start, tag); 50 } 51 52 } // namespace __hwasan 53