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Diffstat (limited to 'lib/hwasan/hwasan_report.cpp')
| -rw-r--r-- | lib/hwasan/hwasan_report.cpp | 467 |
1 files changed, 467 insertions, 0 deletions
diff --git a/lib/hwasan/hwasan_report.cpp b/lib/hwasan/hwasan_report.cpp new file mode 100644 index 000000000..fa2fff742 --- /dev/null +++ b/lib/hwasan/hwasan_report.cpp @@ -0,0 +1,467 @@ +//===-- hwasan_report.cpp -------------------------------------------------===// +// +// 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 HWAddressSanitizer. +// +// Error reporting. +//===----------------------------------------------------------------------===// + +#include "hwasan.h" +#include "hwasan_allocator.h" +#include "hwasan_mapping.h" +#include "hwasan_report.h" +#include "hwasan_thread.h" +#include "hwasan_thread_list.h" +#include "sanitizer_common/sanitizer_allocator_internal.h" +#include "sanitizer_common/sanitizer_common.h" +#include "sanitizer_common/sanitizer_flags.h" +#include "sanitizer_common/sanitizer_mutex.h" +#include "sanitizer_common/sanitizer_report_decorator.h" +#include "sanitizer_common/sanitizer_stackdepot.h" +#include "sanitizer_common/sanitizer_stacktrace_printer.h" +#include "sanitizer_common/sanitizer_symbolizer.h" + +using namespace __sanitizer; + +namespace __hwasan { + +class ScopedReport { + public: + ScopedReport(bool fatal = false) : error_message_(1), fatal(fatal) { + BlockingMutexLock lock(&error_message_lock_); + error_message_ptr_ = fatal ? &error_message_ : nullptr; + ++hwasan_report_count; + } + + ~ScopedReport() { + { + BlockingMutexLock lock(&error_message_lock_); + if (fatal) + SetAbortMessage(error_message_.data()); + error_message_ptr_ = nullptr; + } + if (common_flags()->print_module_map >= 2 || + (fatal && common_flags()->print_module_map)) + DumpProcessMap(); + if (fatal) + Die(); + } + + static void MaybeAppendToErrorMessage(const char *msg) { + BlockingMutexLock lock(&error_message_lock_); + if (!error_message_ptr_) + return; + uptr len = internal_strlen(msg); + uptr old_size = error_message_ptr_->size(); + error_message_ptr_->resize(old_size + len); + // overwrite old trailing '\0', keep new trailing '\0' untouched. + internal_memcpy(&(*error_message_ptr_)[old_size - 1], msg, len); + } + private: + ScopedErrorReportLock error_report_lock_; + InternalMmapVector<char> error_message_; + bool fatal; + + static InternalMmapVector<char> *error_message_ptr_; + static BlockingMutex error_message_lock_; +}; + +InternalMmapVector<char> *ScopedReport::error_message_ptr_; +BlockingMutex ScopedReport::error_message_lock_; + +// If there is an active ScopedReport, append to its error message. +void AppendToErrorMessageBuffer(const char *buffer) { + ScopedReport::MaybeAppendToErrorMessage(buffer); +} + +static StackTrace GetStackTraceFromId(u32 id) { + CHECK(id); + StackTrace res = StackDepotGet(id); + CHECK(res.trace); + return res; +} + +// A RAII object that holds a copy of the current thread stack ring buffer. +// The actual stack buffer may change while we are iterating over it (for +// example, Printf may call syslog() which can itself be built with hwasan). +class SavedStackAllocations { + public: + SavedStackAllocations(StackAllocationsRingBuffer *rb) { + uptr size = rb->size() * sizeof(uptr); + void *storage = + MmapAlignedOrDieOnFatalError(size, size * 2, "saved stack allocations"); + new (&rb_) StackAllocationsRingBuffer(*rb, storage); + } + + ~SavedStackAllocations() { + StackAllocationsRingBuffer *rb = get(); + UnmapOrDie(rb->StartOfStorage(), rb->size() * sizeof(uptr)); + } + + StackAllocationsRingBuffer *get() { + return (StackAllocationsRingBuffer *)&rb_; + } + + private: + uptr rb_; +}; + +class Decorator: public __sanitizer::SanitizerCommonDecorator { + public: + Decorator() : SanitizerCommonDecorator() { } + const char *Access() { return Blue(); } + const char *Allocation() const { return Magenta(); } + const char *Origin() const { return Magenta(); } + const char *Name() const { return Green(); } + const char *Location() { return Green(); } + const char *Thread() { return Green(); } +}; + +// Returns the index of the rb element that matches tagged_addr (plus one), +// or zero if found nothing. +uptr FindHeapAllocation(HeapAllocationsRingBuffer *rb, + uptr tagged_addr, + HeapAllocationRecord *har) { + if (!rb) return 0; + for (uptr i = 0, size = rb->size(); i < size; i++) { + auto h = (*rb)[i]; + if (h.tagged_addr <= tagged_addr && + h.tagged_addr + h.requested_size > tagged_addr) { + *har = h; + return i + 1; + } + } + return 0; +} + +void PrintAddressDescription( + uptr tagged_addr, uptr access_size, + StackAllocationsRingBuffer *current_stack_allocations) { + Decorator d; + int num_descriptions_printed = 0; + uptr untagged_addr = UntagAddr(tagged_addr); + + // Print some very basic information about the address, if it's a heap. + HwasanChunkView chunk = FindHeapChunkByAddress(untagged_addr); + if (uptr beg = chunk.Beg()) { + uptr size = chunk.ActualSize(); + Printf("%s[%p,%p) is a %s %s heap chunk; " + "size: %zd offset: %zd\n%s", + d.Location(), + beg, beg + size, + chunk.FromSmallHeap() ? "small" : "large", + chunk.IsAllocated() ? "allocated" : "unallocated", + size, untagged_addr - beg, + d.Default()); + } + + // Check if this looks like a heap buffer overflow by scanning + // the shadow left and right and looking for the first adjacent + // object with a different memory tag. If that tag matches addr_tag, + // check the allocator if it has a live chunk there. + tag_t addr_tag = GetTagFromPointer(tagged_addr); + tag_t *tag_ptr = reinterpret_cast<tag_t*>(MemToShadow(untagged_addr)); + if (*tag_ptr != addr_tag) { // should be true usually. + tag_t *left = tag_ptr, *right = tag_ptr; + // scan left. + for (int i = 0; i < 1000 && *left == *tag_ptr; i++, left--){} + // scan right. + for (int i = 0; i < 1000 && *right == *tag_ptr; i++, right++){} + // Chose the object that has addr_tag and that is closer to addr. + tag_t *candidate = nullptr; + if (*right == addr_tag && *left == addr_tag) + candidate = right - tag_ptr < tag_ptr - left ? right : left; + else if (*right == addr_tag) + candidate = right; + else if (*left == addr_tag) + candidate = left; + + if (candidate) { + uptr mem = ShadowToMem(reinterpret_cast<uptr>(candidate)); + HwasanChunkView chunk = FindHeapChunkByAddress(mem); + if (chunk.IsAllocated()) { + Printf("%s", d.Location()); + Printf( + "%p is located %zd bytes to the %s of %zd-byte region [%p,%p)\n", + untagged_addr, + candidate == left ? untagged_addr - chunk.End() + : chunk.Beg() - untagged_addr, + candidate == right ? "left" : "right", chunk.UsedSize(), + chunk.Beg(), chunk.End()); + Printf("%s", d.Allocation()); + Printf("allocated here:\n"); + Printf("%s", d.Default()); + GetStackTraceFromId(chunk.GetAllocStackId()).Print(); + num_descriptions_printed++; + } + } + } + + hwasanThreadList().VisitAllLiveThreads([&](Thread *t) { + // Scan all threads' ring buffers to find if it's a heap-use-after-free. + HeapAllocationRecord har; + if (uptr D = FindHeapAllocation(t->heap_allocations(), tagged_addr, &har)) { + Printf("%s", d.Location()); + Printf("%p is located %zd bytes inside of %zd-byte region [%p,%p)\n", + untagged_addr, untagged_addr - UntagAddr(har.tagged_addr), + har.requested_size, UntagAddr(har.tagged_addr), + UntagAddr(har.tagged_addr) + har.requested_size); + Printf("%s", d.Allocation()); + Printf("freed by thread T%zd here:\n", t->unique_id()); + Printf("%s", d.Default()); + GetStackTraceFromId(har.free_context_id).Print(); + + Printf("%s", d.Allocation()); + Printf("previously allocated here:\n", t); + Printf("%s", d.Default()); + GetStackTraceFromId(har.alloc_context_id).Print(); + + // Print a developer note: the index of this heap object + // in the thread's deallocation ring buffer. + Printf("hwasan_dev_note_heap_rb_distance: %zd %zd\n", D, + flags()->heap_history_size); + + t->Announce(); + num_descriptions_printed++; + } + + // Very basic check for stack memory. + if (t->AddrIsInStack(untagged_addr)) { + Printf("%s", d.Location()); + Printf("Address %p is located in stack of thread T%zd\n", untagged_addr, + t->unique_id()); + Printf("%s", d.Default()); + t->Announce(); + + // Temporary report section, needs to be improved. + Printf("Previously allocated frames:\n"); + auto *sa = (t == GetCurrentThread() && current_stack_allocations) + ? current_stack_allocations + : t->stack_allocations(); + uptr frames = Min((uptr)flags()->stack_history_size, sa->size()); + InternalScopedString frame_desc(GetPageSizeCached() * 2); + for (uptr i = 0; i < frames; i++) { + uptr record = (*sa)[i]; + if (!record) + break; + uptr sp = (record >> 48) << 4; + uptr pc_mask = (1ULL << 48) - 1; + uptr pc = record & pc_mask; + if (SymbolizedStack *frame = Symbolizer::GetOrInit()->SymbolizePC(pc)) { + frame_desc.append(" sp: 0x%zx ", sp); + RenderFrame(&frame_desc, "#%n %p %F %L\n", 0, frame->info, + common_flags()->symbolize_vs_style, + common_flags()->strip_path_prefix); + frame->ClearAll(); + if (auto Descr = GetStackFrameDescr(pc)) + frame_desc.append(" %s\n", Descr); + } + Printf("%s", frame_desc.data()); + frame_desc.clear(); + } + + num_descriptions_printed++; + } + }); + + // Print the remaining threads, as an extra information, 1 line per thread. + hwasanThreadList().VisitAllLiveThreads([&](Thread *t) { t->Announce(); }); + + if (!num_descriptions_printed) + // We exhausted our possibilities. Bail out. + Printf("HWAddressSanitizer can not describe address in more detail.\n"); +} + +void ReportStats() {} + +static void PrintTagsAroundAddr(tag_t *tag_ptr) { + Printf( + "Memory tags around the buggy address (one tag corresponds to %zd " + "bytes):\n", kShadowAlignment); + + const uptr row_len = 16; // better be power of two. + const uptr num_rows = 17; + tag_t *center_row_beg = reinterpret_cast<tag_t *>( + RoundDownTo(reinterpret_cast<uptr>(tag_ptr), row_len)); + tag_t *beg_row = center_row_beg - row_len * (num_rows / 2); + tag_t *end_row = center_row_beg + row_len * (num_rows / 2); + InternalScopedString s(GetPageSizeCached() * 8); + for (tag_t *row = beg_row; row < end_row; row += row_len) { + s.append("%s", row == center_row_beg ? "=>" : " "); + for (uptr i = 0; i < row_len; i++) { + s.append("%s", row + i == tag_ptr ? "[" : " "); + s.append("%02x", row[i]); + s.append("%s", row + i == tag_ptr ? "]" : " "); + } + s.append("%s\n", row == center_row_beg ? "<=" : " "); + } + Printf("%s", s.data()); +} + +void ReportInvalidFree(StackTrace *stack, uptr tagged_addr) { + ScopedReport R(flags()->halt_on_error); + + uptr untagged_addr = UntagAddr(tagged_addr); + tag_t ptr_tag = GetTagFromPointer(tagged_addr); + tag_t *tag_ptr = reinterpret_cast<tag_t*>(MemToShadow(untagged_addr)); + tag_t mem_tag = *tag_ptr; + Decorator d; + Printf("%s", d.Error()); + uptr pc = stack->size ? stack->trace[0] : 0; + const char *bug_type = "invalid-free"; + Report("ERROR: %s: %s on address %p at pc %p\n", SanitizerToolName, bug_type, + untagged_addr, pc); + Printf("%s", d.Access()); + Printf("tags: %02x/%02x (ptr/mem)\n", ptr_tag, mem_tag); + Printf("%s", d.Default()); + + stack->Print(); + + PrintAddressDescription(tagged_addr, 0, nullptr); + + PrintTagsAroundAddr(tag_ptr); + + ReportErrorSummary(bug_type, stack); +} + +void ReportTailOverwritten(StackTrace *stack, uptr tagged_addr, uptr orig_size, + uptr tail_size, const u8 *expected) { + ScopedReport R(flags()->halt_on_error); + Decorator d; + uptr untagged_addr = UntagAddr(tagged_addr); + Printf("%s", d.Error()); + const char *bug_type = "alocation-tail-overwritten"; + Report("ERROR: %s: %s; heap object [%p,%p) of size %zd\n", SanitizerToolName, + bug_type, untagged_addr, untagged_addr + orig_size, orig_size); + Printf("\n%s", d.Default()); + stack->Print(); + HwasanChunkView chunk = FindHeapChunkByAddress(untagged_addr); + if (chunk.Beg()) { + Printf("%s", d.Allocation()); + Printf("allocated here:\n"); + Printf("%s", d.Default()); + GetStackTraceFromId(chunk.GetAllocStackId()).Print(); + } + + InternalScopedString s(GetPageSizeCached() * 8); + CHECK_GT(tail_size, 0U); + CHECK_LT(tail_size, kShadowAlignment); + u8 *tail = reinterpret_cast<u8*>(untagged_addr + orig_size); + s.append("Tail contains: "); + for (uptr i = 0; i < kShadowAlignment - tail_size; i++) + s.append(".. "); + for (uptr i = 0; i < tail_size; i++) + s.append("%02x ", tail[i]); + s.append("\n"); + s.append("Expected: "); + for (uptr i = 0; i < kShadowAlignment - tail_size; i++) + s.append(".. "); + for (uptr i = 0; i < tail_size; i++) + s.append("%02x ", expected[i]); + s.append("\n"); + s.append(" "); + for (uptr i = 0; i < kShadowAlignment - tail_size; i++) + s.append(" "); + for (uptr i = 0; i < tail_size; i++) + s.append("%s ", expected[i] != tail[i] ? "^^" : " "); + + s.append("\nThis error occurs when a buffer overflow overwrites memory\n" + "to the right of a heap object, but within the %zd-byte granule, e.g.\n" + " char *x = new char[20];\n" + " x[25] = 42;\n" + "By default %s does not detect such bugs at the time of write,\n" + "but can detect them at the time of free/delete.\n" + "To disable this feature set HWASAN_OPTIONS=free_checks_tail_magic=0;\n" + "To enable checking at the time of access, set " + "HWASAN_OPTIONS=malloc_align_right to non-zero\n\n", + kShadowAlignment, SanitizerToolName); + Printf("%s", s.data()); + GetCurrentThread()->Announce(); + + tag_t *tag_ptr = reinterpret_cast<tag_t*>(MemToShadow(untagged_addr)); + PrintTagsAroundAddr(tag_ptr); + + ReportErrorSummary(bug_type, stack); +} + +void ReportTagMismatch(StackTrace *stack, uptr tagged_addr, uptr access_size, + bool is_store, bool fatal, uptr *registers_frame) { + ScopedReport R(fatal); + SavedStackAllocations current_stack_allocations( + GetCurrentThread()->stack_allocations()); + + Decorator d; + Printf("%s", d.Error()); + uptr untagged_addr = UntagAddr(tagged_addr); + // TODO: when possible, try to print heap-use-after-free, etc. + const char *bug_type = "tag-mismatch"; + uptr pc = stack->size ? stack->trace[0] : 0; + Report("ERROR: %s: %s on address %p at pc %p\n", SanitizerToolName, bug_type, + untagged_addr, pc); + + Thread *t = GetCurrentThread(); + + sptr offset = + __hwasan_test_shadow(reinterpret_cast<void *>(tagged_addr), access_size); + CHECK(offset >= 0 && offset < static_cast<sptr>(access_size)); + tag_t ptr_tag = GetTagFromPointer(tagged_addr); + tag_t *tag_ptr = + reinterpret_cast<tag_t *>(MemToShadow(untagged_addr + offset)); + tag_t mem_tag = *tag_ptr; + + Printf("%s", d.Access()); + Printf("%s of size %zu at %p tags: %02x/%02x (ptr/mem) in thread T%zd\n", + is_store ? "WRITE" : "READ", access_size, untagged_addr, ptr_tag, + mem_tag, t->unique_id()); + if (offset != 0) + Printf("Invalid access starting at offset [%zu, %zu)\n", offset, + Min(access_size, static_cast<uptr>(offset) + (1 << kShadowScale))); + Printf("%s", d.Default()); + + stack->Print(); + + PrintAddressDescription(tagged_addr, access_size, + current_stack_allocations.get()); + t->Announce(); + + PrintTagsAroundAddr(tag_ptr); + + if (registers_frame) + ReportRegisters(registers_frame, pc); + + ReportErrorSummary(bug_type, stack); +} + +// See the frame breakdown defined in __hwasan_tag_mismatch (from +// hwasan_tag_mismatch_aarch64.S). +void ReportRegisters(uptr *frame, uptr pc) { + Printf("Registers where the failure occurred (pc %p):\n", pc); + + // We explicitly print a single line (4 registers/line) each iteration to + // reduce the amount of logcat error messages printed. Each Printf() will + // result in a new logcat line, irrespective of whether a newline is present, + // and so we wish to reduce the number of Printf() calls we have to make. + Printf(" x0 %016llx x1 %016llx x2 %016llx x3 %016llx\n", + frame[0], frame[1], frame[2], frame[3]); + Printf(" x4 %016llx x5 %016llx x6 %016llx x7 %016llx\n", + frame[4], frame[5], frame[6], frame[7]); + Printf(" x8 %016llx x9 %016llx x10 %016llx x11 %016llx\n", + frame[8], frame[9], frame[10], frame[11]); + Printf(" x12 %016llx x13 %016llx x14 %016llx x15 %016llx\n", + frame[12], frame[13], frame[14], frame[15]); + Printf(" x16 %016llx x17 %016llx x18 %016llx x19 %016llx\n", + frame[16], frame[17], frame[18], frame[19]); + Printf(" x20 %016llx x21 %016llx x22 %016llx x23 %016llx\n", + frame[20], frame[21], frame[22], frame[23]); + Printf(" x24 %016llx x25 %016llx x26 %016llx x27 %016llx\n", + frame[24], frame[25], frame[26], frame[27]); + Printf(" x28 %016llx x29 %016llx x30 %016llx\n", + frame[28], frame[29], frame[30]); +} + +} // namespace __hwasan |