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[hwasan] Store some report data early #66682

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Sep 21, 2023
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[hwasan] Store some report data early #66682

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65 changes: 40 additions & 25 deletions compiler-rt/lib/hwasan/hwasan_report.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -395,6 +395,7 @@ class BaseReport {
access_size(access_size),
untagged_addr(UntagAddr(tagged_addr)),
ptr_tag(GetTagFromPointer(tagged_addr)),
mismatch_offset(FindMismatchOffset()),
heap(CopyHeapChunk()),
allocations(CopyAllocations()),
candidate(FindBufferOverflowCandidate()),
Expand Down Expand Up @@ -442,6 +443,7 @@ class BaseReport {
tag_t short_tags[ARRAY_SIZE(tags)] = {};
};

sptr FindMismatchOffset() const;
Shadow CopyShadow() const;
tag_t GetTagCopy(uptr addr) const;
tag_t GetShortTagCopy(uptr addr) const;
Expand All @@ -461,6 +463,7 @@ class BaseReport {
const uptr access_size = 0;
const uptr untagged_addr = 0;
const tag_t ptr_tag = 0;
const sptr mismatch_offset = 0;

const HeapChunk heap;
const Allocations allocations;
Expand All @@ -469,6 +472,37 @@ class BaseReport {
const Shadow shadow;
};

sptr BaseReport::FindMismatchOffset() const {
if (!access_size)
return 0;
sptr offset =
__hwasan_test_shadow(reinterpret_cast<void *>(tagged_addr), access_size);
CHECK_GE(offset, 0);
CHECK_LT(offset, static_cast<sptr>(access_size));
tag_t *tag_ptr =
reinterpret_cast<tag_t *>(MemToShadow(untagged_addr + offset));
tag_t mem_tag = *tag_ptr;

if (mem_tag && mem_tag < kShadowAlignment) {
tag_t *granule_ptr = reinterpret_cast<tag_t *>((untagged_addr + offset) &
~(kShadowAlignment - 1));
// If offset is 0, (untagged_addr + offset) is not aligned to granules.
// This is the offset of the leftmost accessed byte within the bad granule.
u8 in_granule_offset = (untagged_addr + offset) & (kShadowAlignment - 1);
tag_t short_tag = granule_ptr[kShadowAlignment - 1];
// The first mismatch was a short granule that matched the ptr_tag.
if (short_tag == ptr_tag) {
// If the access starts after the end of the short granule, then the first
// bad byte is the first byte of the access; otherwise it is the first
// byte past the end of the short granule
if (mem_tag > in_granule_offset) {
offset += mem_tag - in_granule_offset;
}
}
}
return offset;
}

BaseReport::Shadow BaseReport::CopyShadow() const {
Shadow result;
if (!MemIsApp(untagged_addr))
Expand Down Expand Up @@ -917,31 +951,12 @@ TagMismatchReport::~TagMismatchReport() {

Thread *t = GetCurrentThread();

sptr offset =
__hwasan_test_shadow(reinterpret_cast<void *>(tagged_addr), access_size);
CHECK_GE(offset, 0);
CHECK_LT(offset, static_cast<sptr>(access_size));
tag_t *tag_ptr =
reinterpret_cast<tag_t *>(MemToShadow(untagged_addr + offset));
tag_t mem_tag = *tag_ptr;
tag_t mem_tag = GetTagCopy(MemToShadow(untagged_addr + mismatch_offset));

Printf("%s", d.Access());
if (mem_tag && mem_tag < kShadowAlignment) {
tag_t *granule_ptr = reinterpret_cast<tag_t *>((untagged_addr + offset) &
~(kShadowAlignment - 1));
// If offset is 0, (untagged_addr + offset) is not aligned to granules.
// This is the offset of the leftmost accessed byte within the bad granule.
u8 in_granule_offset = (untagged_addr + offset) & (kShadowAlignment - 1);
tag_t short_tag = granule_ptr[kShadowAlignment - 1];
// The first mismatch was a short granule that matched the ptr_tag.
if (short_tag == ptr_tag) {
// If the access starts after the end of the short granule, then the first
// bad byte is the first byte of the access; otherwise it is the first
// byte past the end of the short granule
if (mem_tag > in_granule_offset) {
offset += mem_tag - in_granule_offset;
}
}
tag_t short_tag =
GetShortTagCopy(MemToShadow(untagged_addr + mismatch_offset));
Printf(
"%s of size %zu at %p tags: %02x/%02x(%02x) (ptr/mem) in thread T%zd\n",
is_store ? "WRITE" : "READ", access_size, untagged_addr, ptr_tag,
Expand All @@ -951,16 +966,16 @@ TagMismatchReport::~TagMismatchReport() {
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\n", offset);
if (mismatch_offset)
Printf("Invalid access starting at offset %zu\n", mismatch_offset);
Printf("%s", d.Default());

stack->Print();

PrintAddressDescription();
t->Announce();

PrintTags(untagged_addr + offset);
PrintTags(untagged_addr + mismatch_offset);

if (registers_frame)
ReportRegisters(registers_frame, pc);
Expand Down