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[profile] Fix bounds checks in profile merging #118782

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Merged
merged 2 commits into from
Dec 6, 2024
Merged

[profile] Fix bounds checks in profile merging #118782

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[profile] Fix bounds checks in profile merging
nikic Dec 5, 2024
b6d1b81
Adjust one more place and fix warning
nikic Dec 5, 2024
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21 changes: 14 additions & 7 deletions compiler-rt/lib/profile/InstrProfilingMerge.c
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Original file line number Diff line number Diff line change
Expand Up @@ -127,6 +127,12 @@ getDistanceFromCounterToValueProf(const __llvm_profile_header *const Header) {
PaddingBytesAfterVNamesSize;
}

// Add offset to pointer without assuming that the addition does not overflow.
// This allows performing bounds checks by checking the result of the addition.
static const char *ptr_add_with_overflow(const char *p, size_t offset) {
return (const char *)((uintptr_t)p + offset);
}

COMPILER_RT_VISIBILITY
int __llvm_profile_merge_from_buffer(const char *ProfileData,
uint64_t ProfileSize) {
Expand Down Expand Up @@ -154,9 +160,10 @@ int __llvm_profile_merge_from_buffer(const char *ProfileData,
SrcCountersStart = (char *)SrcDataEnd;
SrcCountersEnd = SrcCountersStart +
Header->NumCounters * __llvm_profile_counter_entry_size();
SrcBitmapStart = SrcCountersEnd + __llvm_profile_get_num_padding_bytes(
SrcCountersEnd - SrcCountersStart);
SrcNameStart = SrcBitmapStart + Header->NumBitmapBytes;
SrcBitmapStart = ptr_add_with_overflow(
SrcCountersEnd,
__llvm_profile_get_num_padding_bytes(SrcCountersEnd - SrcCountersStart));
SrcNameStart = ptr_add_with_overflow(SrcBitmapStart, Header->NumBitmapBytes);
SrcValueProfDataStart =
SrcNameStart + getDistanceFromCounterToValueProf(Header);
if (SrcNameStart < SrcCountersStart || SrcNameStart < SrcBitmapStart)
Expand Down Expand Up @@ -200,8 +207,8 @@ int __llvm_profile_merge_from_buffer(const char *ProfileData,
// CountersDelta computes the offset into the in-buffer counter section.
//
// On WIN64, CountersDelta is truncated as well, so no need for signext.
char *SrcCounters =
SrcCountersStart + ((uintptr_t)SrcData->CounterPtr - CountersDelta);
const char *SrcCounters = ptr_add_with_overflow(
SrcCountersStart, (uintptr_t)SrcData->CounterPtr - CountersDelta);
// CountersDelta needs to be decreased as we advance to the next data
// record.
CountersDelta -= sizeof(*SrcData);
Expand All @@ -220,8 +227,8 @@ int __llvm_profile_merge_from_buffer(const char *ProfileData,
}
}

const char *SrcBitmap =
SrcBitmapStart + ((uintptr_t)SrcData->BitmapPtr - BitmapDelta);
const char *SrcBitmap = ptr_add_with_overflow(
SrcBitmapStart, (uintptr_t)SrcData->BitmapPtr - BitmapDelta);
// BitmapDelta also needs to be decreased as we advance to the next data
// record.
BitmapDelta -= sizeof(*SrcData);
Expand Down
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