llvmbot wrote:
<!--LLVM PR SUMMARY COMMENT--> @llvm/pr-subscribers-compiler-rt-sanitizer Author: Vitaly Buka (vitalybuka) <details> <summary>Changes</summary> A layer over `TryMemCpy` to copy only availible pages. --- Full diff: https://github.com/llvm/llvm-project/pull/112794.diff 3 Files Affected: - (modified) compiler-rt/lib/sanitizer_common/sanitizer_common.h (+2) - (modified) compiler-rt/lib/sanitizer_common/sanitizer_common_libcdep.cpp (+26) - (modified) compiler-rt/lib/sanitizer_common/tests/sanitizer_posix_test.cpp (+28-6) ``````````diff diff --git a/compiler-rt/lib/sanitizer_common/sanitizer_common.h b/compiler-rt/lib/sanitizer_common/sanitizer_common.h index 9b1e58f5e7a61d..a7b6a4033a5276 100644 --- a/compiler-rt/lib/sanitizer_common/sanitizer_common.h +++ b/compiler-rt/lib/sanitizer_common/sanitizer_common.h @@ -273,6 +273,8 @@ bool IsAccessibleMemoryRange(uptr beg, uptr size); // Returns true if we can read a memory range starting at `src`, and copies // content into `dest`. bool TryMemCpy(void *dest, const void *src, uptr n); +// Copies accesible memory, and zero fill the rest. +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 684720963a8dcb..3ad5aaa0a7d4ab 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<uptr>(src); + uptr b_up = RoundUpTo(b, page_size); + + uptr e = reinterpret_cast<uptr>(src) + n; + uptr e_down = RoundDownTo(e, page_size); + + auto copy_or_zero = [dest, src](uptr b, uptr e) { + uptr d = reinterpret_cast<uptr>(dest) + (b - reinterpret_cast<uptr>(src)); + if (!TryMemCpy(reinterpret_cast<void *>(d), reinterpret_cast<void *>(b), + e - b)) + internal_memset(reinterpret_cast<void *>(d), 0, e - b); + }; + + 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 03a841a6f438cb..5016b09c15307f 100644 --- a/compiler-rt/lib/sanitizer_common/tests/sanitizer_posix_test.cpp +++ b/compiler-rt/lib/sanitizer_common/tests/sanitizer_posix_test.cpp @@ -127,19 +127,41 @@ TEST(SanitizerCommon, TryMemCpyNull) { EXPECT_FALSE(TryMemCpy(dst.data(), nullptr, dst.size())); } -TEST(SanitizerCommon, TryMemCpyProtected) { +TEST(SanitizerCommon, MemCpyAccessible) { + const int page_num = 1000; const int page_size = GetPageSize(); - InternalMmapVector<char> src(3 * page_size); + InternalMmapVector<char> src(page_num * page_size); std::iota(src.begin(), src.end(), 123); std::vector<char> dst; - // Protect the middle page. - mprotect(src.data() + page_size, page_size, PROT_NONE); + std::vector<char> 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())); - mprotect(src.data() + page_size, page_size, PROT_READ | PROT_WRITE); - EXPECT_TRUE(std::equal(dst.begin(), dst.end(), src.begin())); + // 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 `````````` </details> https://github.com/llvm/llvm-project/pull/112794 _______________________________________________ llvm-branch-commits mailing list llvm-branch-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-branch-commits
