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//===-- msan_poisoning.cpp --------------------------------------*- C++ -*-===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// This file is a part of MemorySanitizer.
//
//===----------------------------------------------------------------------===//
#include "msan_poisoning.h"
#include "interception/interception.h"
#include "msan_origin.h"
#include "msan_thread.h"
#include "sanitizer_common/sanitizer_common.h"
DECLARE_REAL(void *, memset, void *dest, int c, uptr n)
DECLARE_REAL(void *, memcpy, void *dest, const void *src, uptr n)
DECLARE_REAL(void *, memmove, void *dest, const void *src, uptr n)
namespace __msan {
u32 GetOriginIfPoisoned(uptr addr, uptr size) {
unsigned char *s = (unsigned char *)MEM_TO_SHADOW(addr);
for (uptr i = 0; i < size; ++i)
if (s[i]) return *(u32 *)SHADOW_TO_ORIGIN(((uptr)s + i) & ~3UL);
return 0;
}
void SetOriginIfPoisoned(uptr addr, uptr src_shadow, uptr size,
u32 src_origin) {
uptr dst_s = MEM_TO_SHADOW(addr);
uptr src_s = src_shadow;
uptr src_s_end = src_s + size;
for (; src_s < src_s_end; ++dst_s, ++src_s)
if (*(u8 *)src_s) *(u32 *)SHADOW_TO_ORIGIN(dst_s & ~3UL) = src_origin;
}
void CopyOrigin(const void *dst, const void *src, uptr size,
StackTrace *stack) {
if (!MEM_IS_APP(dst) || !MEM_IS_APP(src)) return;
uptr d = (uptr)dst;
uptr beg = d & ~3UL;
// Copy left unaligned origin if that memory is poisoned.
if (beg < d) {
u32 o = GetOriginIfPoisoned((uptr)src, beg + 4 - d);
if (o) {
if (__msan_get_track_origins() > 1) o = ChainOrigin(o, stack);
*(u32 *)MEM_TO_ORIGIN(beg) = o;
}
beg += 4;
}
uptr end = (d + size) & ~3UL;
// If both ends fall into the same 4-byte slot, we are done.
if (end < beg) return;
// Copy right unaligned origin if that memory is poisoned.
if (end < d + size) {
u32 o = GetOriginIfPoisoned((uptr)src + (end - d), (d + size) - end);
if (o) {
if (__msan_get_track_origins() > 1) o = ChainOrigin(o, stack);
*(u32 *)MEM_TO_ORIGIN(end) = o;
}
}
if (beg < end) {
// Align src up.
uptr s = ((uptr)src + 3) & ~3UL;
// FIXME: factor out to msan_copy_origin_aligned
if (__msan_get_track_origins() > 1) {
u32 *src = (u32 *)MEM_TO_ORIGIN(s);
u32 *src_s = (u32 *)MEM_TO_SHADOW(s);
u32 *src_end = (u32 *)MEM_TO_ORIGIN(s + (end - beg));
u32 *dst = (u32 *)MEM_TO_ORIGIN(beg);
u32 src_o = 0;
u32 dst_o = 0;
for (; src < src_end; ++src, ++src_s, ++dst) {
if (!*src_s) continue;
if (*src != src_o) {
src_o = *src;
dst_o = ChainOrigin(src_o, stack);
}
*dst = dst_o;
}
} else {
REAL(memcpy)((void *)MEM_TO_ORIGIN(beg), (void *)MEM_TO_ORIGIN(s),
end - beg);
}
}
}
void ReverseCopyOrigin(const void *dst, const void *src, uptr size,
StackTrace *stack) {
if (!MEM_IS_APP(dst) || !MEM_IS_APP(src))
return;
uptr d = (uptr)dst;
uptr end = (d + size) & ~3UL;
// Copy right unaligned origin if that memory is poisoned.
if (end < d + size) {
u32 o = GetOriginIfPoisoned((uptr)src + (end - d), (d + size) - end);
if (o) {
if (__msan_get_track_origins() > 1)
o = ChainOrigin(o, stack);
*(u32 *)MEM_TO_ORIGIN(end) = o;
}
}
uptr beg = d & ~3UL;
if (beg + 4 < end) {
// Align src up.
uptr s = ((uptr)src + 3) & ~3UL;
if (__msan_get_track_origins() > 1) {
u32 *src = (u32 *)MEM_TO_ORIGIN(s + end - beg - 4);
u32 *src_s = (u32 *)MEM_TO_SHADOW(s + end - beg - 4);
u32 *src_begin = (u32 *)MEM_TO_ORIGIN(s);
u32 *dst = (u32 *)MEM_TO_ORIGIN(end - 4);
u32 src_o = 0;
u32 dst_o = 0;
for (; src >= src_begin; --src, --src_s, --dst) {
if (!*src_s)
continue;
if (*src != src_o) {
src_o = *src;
dst_o = ChainOrigin(src_o, stack);
}
*dst = dst_o;
}
} else {
REAL(memmove)
((void *)MEM_TO_ORIGIN(beg), (void *)MEM_TO_ORIGIN(s), end - beg - 4);
}
}
// Copy left unaligned origin if that memory is poisoned.
if (beg < d) {
u32 o = GetOriginIfPoisoned((uptr)src, beg + 4 - d);
if (o) {
if (__msan_get_track_origins() > 1)
o = ChainOrigin(o, stack);
*(u32 *)MEM_TO_ORIGIN(beg) = o;
}
}
}
void MoveOrigin(const void *dst, const void *src, uptr size,
StackTrace *stack) {
// If destination origin range overlaps with source origin range, move
// origins by coping origins in a reverse order; otherwise, copy origins in
// a normal order.
uptr src_aligned_beg = reinterpret_cast<uptr>(src) & ~3UL;
uptr src_aligned_end = (reinterpret_cast<uptr>(src) + size) & ~3UL;
uptr dst_aligned_beg = reinterpret_cast<uptr>(dst) & ~3UL;
if (dst_aligned_beg < src_aligned_end && dst_aligned_beg >= src_aligned_beg)
return ReverseCopyOrigin(dst, src, size, stack);
return CopyOrigin(dst, src, size, stack);
}
void MoveShadowAndOrigin(const void *dst, const void *src, uptr size,
StackTrace *stack) {
if (!MEM_IS_APP(dst)) return;
if (!MEM_IS_APP(src)) return;
if (src == dst) return;
// MoveOrigin transfers origins by refering to their shadows. So we
// need to move origins before moving shadows.
if (__msan_get_track_origins())
MoveOrigin(dst, src, size, stack);
REAL(memmove)((void *)MEM_TO_SHADOW((uptr)dst),
(void *)MEM_TO_SHADOW((uptr)src), size);
}
void CopyShadowAndOrigin(const void *dst, const void *src, uptr size,
StackTrace *stack) {
if (!MEM_IS_APP(dst)) return;
if (!MEM_IS_APP(src)) return;
// Because origin's range is slightly larger than app range, memcpy may also
// cause overlapped origin ranges.
REAL(memcpy)((void *)MEM_TO_SHADOW((uptr)dst),
(void *)MEM_TO_SHADOW((uptr)src), size);
if (__msan_get_track_origins())
MoveOrigin(dst, src, size, stack);
}
void CopyMemory(void *dst, const void *src, uptr size, StackTrace *stack) {
REAL(memcpy)(dst, src, size);
CopyShadowAndOrigin(dst, src, size, stack);
}
void SetShadow(const void *ptr, uptr size, u8 value) {
uptr PageSize = GetPageSizeCached();
uptr shadow_beg = MEM_TO_SHADOW(ptr);
uptr shadow_end = shadow_beg + size;
if (value ||
shadow_end - shadow_beg < common_flags()->clear_shadow_mmap_threshold) {
REAL(memset)((void *)shadow_beg, value, shadow_end - shadow_beg);
} else {
uptr page_beg = RoundUpTo(shadow_beg, PageSize);
uptr page_end = RoundDownTo(shadow_end, PageSize);
if (page_beg >= page_end) {
REAL(memset)((void *)shadow_beg, 0, shadow_end - shadow_beg);
} else {
if (page_beg != shadow_beg) {
REAL(memset)((void *)shadow_beg, 0, page_beg - shadow_beg);
}
if (page_end != shadow_end) {
REAL(memset)((void *)page_end, 0, shadow_end - page_end);
}
if (!MmapFixedSuperNoReserve(page_beg, page_end - page_beg))
Die();
if (__msan_get_track_origins()) {
// No need to set origin for zero shadow, but we can release pages.
uptr origin_beg = RoundUpTo(MEM_TO_ORIGIN(ptr), PageSize);
if (!MmapFixedSuperNoReserve(origin_beg, page_end - page_beg))
Die();
}
}
}
}
void SetOrigin(const void *dst, uptr size, u32 origin) {
// Origin mapping is 4 bytes per 4 bytes of application memory.
// Here we extend the range such that its left and right bounds are both
// 4 byte aligned.
uptr x = MEM_TO_ORIGIN((uptr)dst);
uptr beg = x & ~3UL; // align down.
uptr end = (x + size + 3) & ~3UL; // align up.
u64 origin64 = ((u64)origin << 32) | origin;
// This is like memset, but the value is 32-bit. We unroll by 2 to write
// 64 bits at once. May want to unroll further to get 128-bit stores.
if (beg & 7ULL) {
*(u32 *)beg = origin;
beg += 4;
}
for (uptr addr = beg; addr < (end & ~7UL); addr += 8) *(u64 *)addr = origin64;
if (end & 7ULL) *(u32 *)(end - 4) = origin;
}
void PoisonMemory(const void *dst, uptr size, StackTrace *stack) {
SetShadow(dst, size, (u8)-1);
if (__msan_get_track_origins()) {
MsanThread *t = GetCurrentThread();
if (t && t->InSignalHandler())
return;
Origin o = Origin::CreateHeapOrigin(stack);
SetOrigin(dst, size, o.raw_id());
}
}
} // namespace __msan
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