| //===-- asan_poisoning.cc -------------------------------------------------===// |
| // |
| // This file is distributed under the University of Illinois Open Source |
| // License. See LICENSE.TXT for details. |
| // |
| //===----------------------------------------------------------------------===// |
| // |
| // This file is a part of AddressSanitizer, an address sanity checker. |
| // |
| // Shadow memory poisoning by ASan RTL and by user application. |
| //===----------------------------------------------------------------------===// |
| |
| #include "asan_poisoning.h" |
| #include "asan_report.h" |
| #include "asan_stack.h" |
| #include "sanitizer_common/sanitizer_libc.h" |
| #include "sanitizer_common/sanitizer_flags.h" |
| |
| namespace __asan { |
| |
| void PoisonShadow(uptr addr, uptr size, u8 value) { |
| if (!flags()->poison_heap) return; |
| CHECK(AddrIsAlignedByGranularity(addr)); |
| CHECK(AddrIsInMem(addr)); |
| CHECK(AddrIsAlignedByGranularity(addr + size)); |
| CHECK(AddrIsInMem(addr + size - SHADOW_GRANULARITY)); |
| CHECK(REAL(memset)); |
| FastPoisonShadow(addr, size, value); |
| } |
| |
| void PoisonShadowPartialRightRedzone(uptr addr, |
| uptr size, |
| uptr redzone_size, |
| u8 value) { |
| if (!flags()->poison_heap) return; |
| CHECK(AddrIsAlignedByGranularity(addr)); |
| CHECK(AddrIsInMem(addr)); |
| FastPoisonShadowPartialRightRedzone(addr, size, redzone_size, value); |
| } |
| |
| struct ShadowSegmentEndpoint { |
| u8 *chunk; |
| s8 offset; // in [0, SHADOW_GRANULARITY) |
| s8 value; // = *chunk; |
| |
| explicit ShadowSegmentEndpoint(uptr address) { |
| chunk = (u8*)MemToShadow(address); |
| offset = address & (SHADOW_GRANULARITY - 1); |
| value = *chunk; |
| } |
| }; |
| |
| void FlushUnneededASanShadowMemory(uptr p, uptr size) { |
| // Since asan's mapping is compacting, the shadow chunk may be |
| // not page-aligned, so we only flush the page-aligned portion. |
| uptr page_size = GetPageSizeCached(); |
| uptr shadow_beg = RoundUpTo(MemToShadow(p), page_size); |
| uptr shadow_end = RoundDownTo(MemToShadow(p + size), page_size); |
| FlushUnneededShadowMemory(shadow_beg, shadow_end - shadow_beg); |
| } |
| |
| } // namespace __asan |
| |
| // ---------------------- Interface ---------------- {{{1 |
| using namespace __asan; // NOLINT |
| |
| // Current implementation of __asan_(un)poison_memory_region doesn't check |
| // that user program (un)poisons the memory it owns. It poisons memory |
| // conservatively, and unpoisons progressively to make sure asan shadow |
| // mapping invariant is preserved (see detailed mapping description here: |
| // http://code.google.com/p/address-sanitizer/wiki/AddressSanitizerAlgorithm). |
| // |
| // * if user asks to poison region [left, right), the program poisons |
| // at least [left, AlignDown(right)). |
| // * if user asks to unpoison region [left, right), the program unpoisons |
| // at most [AlignDown(left), right). |
| void __asan_poison_memory_region(void const volatile *addr, uptr size) { |
| if (!flags()->allow_user_poisoning || size == 0) return; |
| uptr beg_addr = (uptr)addr; |
| uptr end_addr = beg_addr + size; |
| VPrintf(1, "Trying to poison memory region [%p, %p)\n", (void *)beg_addr, |
| (void *)end_addr); |
| ShadowSegmentEndpoint beg(beg_addr); |
| ShadowSegmentEndpoint end(end_addr); |
| if (beg.chunk == end.chunk) { |
| CHECK(beg.offset < end.offset); |
| s8 value = beg.value; |
| CHECK(value == end.value); |
| // We can only poison memory if the byte in end.offset is unaddressable. |
| // No need to re-poison memory if it is poisoned already. |
| if (value > 0 && value <= end.offset) { |
| if (beg.offset > 0) { |
| *beg.chunk = Min(value, beg.offset); |
| } else { |
| *beg.chunk = kAsanUserPoisonedMemoryMagic; |
| } |
| } |
| return; |
| } |
| CHECK(beg.chunk < end.chunk); |
| if (beg.offset > 0) { |
| // Mark bytes from beg.offset as unaddressable. |
| if (beg.value == 0) { |
| *beg.chunk = beg.offset; |
| } else { |
| *beg.chunk = Min(beg.value, beg.offset); |
| } |
| beg.chunk++; |
| } |
| REAL(memset)(beg.chunk, kAsanUserPoisonedMemoryMagic, end.chunk - beg.chunk); |
| // Poison if byte in end.offset is unaddressable. |
| if (end.value > 0 && end.value <= end.offset) { |
| *end.chunk = kAsanUserPoisonedMemoryMagic; |
| } |
| } |
| |
| void __asan_unpoison_memory_region(void const volatile *addr, uptr size) { |
| if (!flags()->allow_user_poisoning || size == 0) return; |
| uptr beg_addr = (uptr)addr; |
| uptr end_addr = beg_addr + size; |
| VPrintf(1, "Trying to unpoison memory region [%p, %p)\n", (void *)beg_addr, |
| (void *)end_addr); |
| ShadowSegmentEndpoint beg(beg_addr); |
| ShadowSegmentEndpoint end(end_addr); |
| if (beg.chunk == end.chunk) { |
| CHECK(beg.offset < end.offset); |
| s8 value = beg.value; |
| CHECK(value == end.value); |
| // We unpoison memory bytes up to enbytes up to end.offset if it is not |
| // unpoisoned already. |
| if (value != 0) { |
| *beg.chunk = Max(value, end.offset); |
| } |
| return; |
| } |
| CHECK(beg.chunk < end.chunk); |
| if (beg.offset > 0) { |
| *beg.chunk = 0; |
| beg.chunk++; |
| } |
| REAL(memset)(beg.chunk, 0, end.chunk - beg.chunk); |
| if (end.offset > 0 && end.value != 0) { |
| *end.chunk = Max(end.value, end.offset); |
| } |
| } |
| |
| int __asan_address_is_poisoned(void const volatile *addr) { |
| return __asan::AddressIsPoisoned((uptr)addr); |
| } |
| |
| uptr __asan_region_is_poisoned(uptr beg, uptr size) { |
| if (!size) return 0; |
| uptr end = beg + size; |
| if (!AddrIsInMem(beg)) return beg; |
| if (!AddrIsInMem(end)) return end; |
| CHECK_LT(beg, end); |
| uptr aligned_b = RoundUpTo(beg, SHADOW_GRANULARITY); |
| uptr aligned_e = RoundDownTo(end, SHADOW_GRANULARITY); |
| uptr shadow_beg = MemToShadow(aligned_b); |
| uptr shadow_end = MemToShadow(aligned_e); |
| // First check the first and the last application bytes, |
| // then check the SHADOW_GRANULARITY-aligned region by calling |
| // mem_is_zero on the corresponding shadow. |
| if (!__asan::AddressIsPoisoned(beg) && |
| !__asan::AddressIsPoisoned(end - 1) && |
| (shadow_end <= shadow_beg || |
| __sanitizer::mem_is_zero((const char *)shadow_beg, |
| shadow_end - shadow_beg))) |
| return 0; |
| // The fast check failed, so we have a poisoned byte somewhere. |
| // Find it slowly. |
| for (; beg < end; beg++) |
| if (__asan::AddressIsPoisoned(beg)) |
| return beg; |
| UNREACHABLE("mem_is_zero returned false, but poisoned byte was not found"); |
| return 0; |
| } |
| |
| #define CHECK_SMALL_REGION(p, size, isWrite) \ |
| do { \ |
| uptr __p = reinterpret_cast<uptr>(p); \ |
| uptr __size = size; \ |
| if (UNLIKELY(__asan::AddressIsPoisoned(__p) || \ |
| __asan::AddressIsPoisoned(__p + __size - 1))) { \ |
| GET_CURRENT_PC_BP_SP; \ |
| uptr __bad = __asan_region_is_poisoned(__p, __size); \ |
| __asan_report_error(pc, bp, sp, __bad, isWrite, __size);\ |
| } \ |
| } while (false); \ |
| |
| |
| extern "C" SANITIZER_INTERFACE_ATTRIBUTE |
| u16 __sanitizer_unaligned_load16(const uu16 *p) { |
| CHECK_SMALL_REGION(p, sizeof(*p), false); |
| return *p; |
| } |
| |
| extern "C" SANITIZER_INTERFACE_ATTRIBUTE |
| u32 __sanitizer_unaligned_load32(const uu32 *p) { |
| CHECK_SMALL_REGION(p, sizeof(*p), false); |
| return *p; |
| } |
| |
| extern "C" SANITIZER_INTERFACE_ATTRIBUTE |
| u64 __sanitizer_unaligned_load64(const uu64 *p) { |
| CHECK_SMALL_REGION(p, sizeof(*p), false); |
| return *p; |
| } |
| |
| extern "C" SANITIZER_INTERFACE_ATTRIBUTE |
| void __sanitizer_unaligned_store16(uu16 *p, u16 x) { |
| CHECK_SMALL_REGION(p, sizeof(*p), true); |
| *p = x; |
| } |
| |
| extern "C" SANITIZER_INTERFACE_ATTRIBUTE |
| void __sanitizer_unaligned_store32(uu32 *p, u32 x) { |
| CHECK_SMALL_REGION(p, sizeof(*p), true); |
| *p = x; |
| } |
| |
| extern "C" SANITIZER_INTERFACE_ATTRIBUTE |
| void __sanitizer_unaligned_store64(uu64 *p, u64 x) { |
| CHECK_SMALL_REGION(p, sizeof(*p), true); |
| *p = x; |
| } |
| |
| // This is a simplified version of __asan_(un)poison_memory_region, which |
| // assumes that left border of region to be poisoned is properly aligned. |
| static void PoisonAlignedStackMemory(uptr addr, uptr size, bool do_poison) { |
| if (size == 0) return; |
| uptr aligned_size = size & ~(SHADOW_GRANULARITY - 1); |
| PoisonShadow(addr, aligned_size, |
| do_poison ? kAsanStackUseAfterScopeMagic : 0); |
| if (size == aligned_size) |
| return; |
| s8 end_offset = (s8)(size - aligned_size); |
| s8* shadow_end = (s8*)MemToShadow(addr + aligned_size); |
| s8 end_value = *shadow_end; |
| if (do_poison) { |
| // If possible, mark all the bytes mapping to last shadow byte as |
| // unaddressable. |
| if (end_value > 0 && end_value <= end_offset) |
| *shadow_end = (s8)kAsanStackUseAfterScopeMagic; |
| } else { |
| // If necessary, mark few first bytes mapping to last shadow byte |
| // as addressable |
| if (end_value != 0) |
| *shadow_end = Max(end_value, end_offset); |
| } |
| } |
| |
| void __asan_poison_stack_memory(uptr addr, uptr size) { |
| VReport(1, "poisoning: %p %zx\n", (void *)addr, size); |
| PoisonAlignedStackMemory(addr, size, true); |
| } |
| |
| void __asan_unpoison_stack_memory(uptr addr, uptr size) { |
| VReport(1, "unpoisoning: %p %zx\n", (void *)addr, size); |
| PoisonAlignedStackMemory(addr, size, false); |
| } |
| |
| void __sanitizer_annotate_contiguous_container(const void *beg_p, |
| const void *end_p, |
| const void *old_mid_p, |
| const void *new_mid_p) { |
| if (!flags()->detect_container_overflow) return; |
| VPrintf(2, "contiguous_container: %p %p %p %p\n", beg_p, end_p, old_mid_p, |
| new_mid_p); |
| uptr beg = reinterpret_cast<uptr>(beg_p); |
| uptr end = reinterpret_cast<uptr>(end_p); |
| uptr old_mid = reinterpret_cast<uptr>(old_mid_p); |
| uptr new_mid = reinterpret_cast<uptr>(new_mid_p); |
| uptr granularity = SHADOW_GRANULARITY; |
| if (!(beg <= old_mid && beg <= new_mid && old_mid <= end && new_mid <= end && |
| IsAligned(beg, granularity))) { |
| GET_STACK_TRACE_FATAL_HERE; |
| ReportBadParamsToAnnotateContiguousContainer(beg, end, old_mid, new_mid, |
| &stack); |
| } |
| CHECK_LE(end - beg, |
| FIRST_32_SECOND_64(1UL << 30, 1UL << 34)); // Sanity check. |
| |
| uptr a = RoundDownTo(Min(old_mid, new_mid), granularity); |
| uptr c = RoundUpTo(Max(old_mid, new_mid), granularity); |
| uptr d1 = RoundDownTo(old_mid, granularity); |
| // uptr d2 = RoundUpTo(old_mid, granularity); |
| // Currently we should be in this state: |
| // [a, d1) is good, [d2, c) is bad, [d1, d2) is partially good. |
| // Make a quick sanity check that we are indeed in this state. |
| // |
| // FIXME: Two of these three checks are disabled until we fix |
| // https://code.google.com/p/address-sanitizer/issues/detail?id=258. |
| // if (d1 != d2) |
| // CHECK_EQ(*(u8*)MemToShadow(d1), old_mid - d1); |
| if (a + granularity <= d1) |
| CHECK_EQ(*(u8*)MemToShadow(a), 0); |
| // if (d2 + granularity <= c && c <= end) |
| // CHECK_EQ(*(u8 *)MemToShadow(c - granularity), |
| // kAsanContiguousContainerOOBMagic); |
| |
| uptr b1 = RoundDownTo(new_mid, granularity); |
| uptr b2 = RoundUpTo(new_mid, granularity); |
| // New state: |
| // [a, b1) is good, [b2, c) is bad, [b1, b2) is partially good. |
| PoisonShadow(a, b1 - a, 0); |
| PoisonShadow(b2, c - b2, kAsanContiguousContainerOOBMagic); |
| if (b1 != b2) { |
| CHECK_EQ(b2 - b1, granularity); |
| *(u8*)MemToShadow(b1) = static_cast<u8>(new_mid - b1); |
| } |
| } |
| |
| int __sanitizer_verify_contiguous_container(const void *beg_p, |
| const void *mid_p, |
| const void *end_p) { |
| if (!flags()->detect_container_overflow) return 1; |
| uptr beg = reinterpret_cast<uptr>(beg_p); |
| uptr end = reinterpret_cast<uptr>(end_p); |
| uptr mid = reinterpret_cast<uptr>(mid_p); |
| CHECK_LE(beg, mid); |
| CHECK_LE(mid, end); |
| // Check some bytes starting from beg, some bytes around mid, and some bytes |
| // ending with end. |
| uptr kMaxRangeToCheck = 32; |
| uptr r1_beg = beg; |
| uptr r1_end = Min(end + kMaxRangeToCheck, mid); |
| uptr r2_beg = Max(beg, mid - kMaxRangeToCheck); |
| uptr r2_end = Min(end, mid + kMaxRangeToCheck); |
| uptr r3_beg = Max(end - kMaxRangeToCheck, mid); |
| uptr r3_end = end; |
| for (uptr i = r1_beg; i < r1_end; i++) |
| if (AddressIsPoisoned(i)) |
| return 0; |
| for (uptr i = r2_beg; i < mid; i++) |
| if (AddressIsPoisoned(i)) |
| return 0; |
| for (uptr i = mid; i < r2_end; i++) |
| if (!AddressIsPoisoned(i)) |
| return 0; |
| for (uptr i = r3_beg; i < r3_end; i++) |
| if (!AddressIsPoisoned(i)) |
| return 0; |
| return 1; |
| } |
| // --- Implementation of LSan-specific functions --- {{{1 |
| namespace __lsan { |
| bool WordIsPoisoned(uptr addr) { |
| return (__asan_region_is_poisoned(addr, sizeof(uptr)) != 0); |
| } |
| } |