diff --git a/compiler-rt/lib/sanitizer_common/sanitizer_common.h b/compiler-rt/lib/sanitizer_common/sanitizer_common.h index 3a28420ed02d7..0b5e68c5fd797 100644 --- a/compiler-rt/lib/sanitizer_common/sanitizer_common.h +++ b/compiler-rt/lib/sanitizer_common/sanitizer_common.h @@ -275,6 +275,8 @@ bool IsAccessibleMemoryRange(uptr beg, uptr size); // the source range cannot be read, in which case the contents of `dest` are // undefined. bool TryMemCpy(void *dest, const void *src, uptr n); +// Copies accessible memory, and zero fill inaccessible. +void MemCpyAccessible(void *dest, const void *src, uptr n); // Error report formatting. const char *StripPathPrefix(const char *filepath, diff --git a/compiler-rt/lib/sanitizer_common/sanitizer_common_libcdep.cpp b/compiler-rt/lib/sanitizer_common/sanitizer_common_libcdep.cpp index 684720963a8dc..f275e81ff0416 100644 --- a/compiler-rt/lib/sanitizer_common/sanitizer_common_libcdep.cpp +++ b/compiler-rt/lib/sanitizer_common/sanitizer_common_libcdep.cpp @@ -219,6 +219,32 @@ static void StopStackDepotBackgroundThread() { static void StopStackDepotBackgroundThread() {} #endif +void MemCpyAccessible(void *dest, const void *src, uptr n) { + if (TryMemCpy(dest, src, n)) + return; + + const uptr page_size = GetPageSize(); + uptr b = reinterpret_cast(src); + uptr b_up = RoundUpTo(b, page_size); + + uptr e = reinterpret_cast(src) + n; + uptr e_down = RoundDownTo(e, page_size); + + auto copy_or_zero = [dest, src](uptr beg, uptr end) { + const uptr udest = reinterpret_cast(dest); + const uptr usrc = reinterpret_cast(src); + void *d = reinterpret_cast(udest + (beg - usrc)); + const uptr size = end - beg; + if (!TryMemCpy(d, reinterpret_cast(beg), size)) + internal_memset(d, 0, size); + }; + + copy_or_zero(b, b_up); + for (uptr p = b_up; p < e_down; p += page_size) + copy_or_zero(p, p + page_size); + copy_or_zero(e_down, e); +} + } // namespace __sanitizer SANITIZER_INTERFACE_WEAK_DEF(void, __sanitizer_sandbox_on_notify, diff --git a/compiler-rt/lib/sanitizer_common/tests/sanitizer_posix_test.cpp b/compiler-rt/lib/sanitizer_common/tests/sanitizer_posix_test.cpp index 658ca60175b3b..5016b09c15307 100644 --- a/compiler-rt/lib/sanitizer_common/tests/sanitizer_posix_test.cpp +++ b/compiler-rt/lib/sanitizer_common/tests/sanitizer_posix_test.cpp @@ -127,6 +127,43 @@ TEST(SanitizerCommon, TryMemCpyNull) { EXPECT_FALSE(TryMemCpy(dst.data(), nullptr, dst.size())); } +TEST(SanitizerCommon, MemCpyAccessible) { + const int page_num = 1000; + const int page_size = GetPageSize(); + InternalMmapVector src(page_num * page_size); + std::iota(src.begin(), src.end(), 123); + std::vector dst; + std::vector exp = {src.begin(), src.end()}; + + // Protect some pages. + for (int i = 7; i < page_num; i *= 2) { + mprotect(src.data() + i * page_size, page_size, PROT_NONE); + std::fill(exp.data() + i * page_size, exp.data() + (i + 1) * page_size, 0); + } + + dst.assign(src.size(), 0); + EXPECT_FALSE(TryMemCpy(dst.data(), src.data(), dst.size())); + + // Full page aligned range with mprotect pages. + dst.assign(src.size(), 0); + MemCpyAccessible(dst.data(), src.data(), dst.size()); + EXPECT_TRUE(std::equal(dst.begin(), dst.end(), exp.begin())); + + // Misaligned range with mprotect pages. + size_t offb = 3; + size_t offe = 7; + dst.assign(src.size() - offb - offe, 0); + MemCpyAccessible(dst.data(), src.data() + offb, dst.size()); + EXPECT_TRUE(std::equal(dst.begin(), dst.end(), exp.begin() + offb)); + + // Misaligned range with ends in mprotect pages. + offb = 3 + 7 * page_size; + offe = 7 + 14 * page_size; + dst.assign(src.size() - offb - offe, 0); + MemCpyAccessible(dst.data(), src.data() + offb, dst.size()); + EXPECT_TRUE(std::equal(dst.begin(), dst.end(), exp.begin() + offb)); +} + } // namespace __sanitizer #endif // SANITIZER_POSIX