fix: add overflow check in ReadBlock block size arithmetic#1312
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Tulgaaaaaaaa wants to merge 2 commits intogoogle:mainfrom
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fix: add overflow check in ReadBlock block size arithmetic#1312Tulgaaaaaaaa wants to merge 2 commits intogoogle:mainfrom
Tulgaaaaaaaa wants to merge 2 commits intogoogle:mainfrom
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ReadBlock() passes handle.size() + kBlockTrailerSize to operator new without checking for arithmetic overflow. A crafted SSTable with a near-SIZE_MAX block handle size causes the addition to wrap around, allocating a tiny buffer while subsequent accesses use the original large offset. Add checks for both size_t truncation (relevant on 32-bit) and addition overflow before the allocation. Bug: CWE-190 (Integer Overflow), CWE-122 (Heap Buffer Overflow)
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Verify that ReadBlock rejects block handles with sizes near SIZE_MAX (overflow check) and handles truncated block reads gracefully.
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Problem
ReadBlock()intable/format.cccomputesn + kBlockTrailerSize(wherekBlockTrailerSize = 5) without checking for arithmetic overflow. The valuencomes fromBlockHandle::size()which is decoded from SSTable file data viaGetVarint64with no range validation.When
nis nearSIZE_MAX, the addition wraps around, causing:new char[wrapped_value])nAdditionally,
handle.size()returnsuint64_twhich is silently truncated tosize_ton 32-bit platforms.Fix
Added two guards before the allocation:
static_cast<size_t>did not lose bits from theuint64_tsourcen + kBlockTrailerSizedoes not wrapsize_tBoth return
Status::Corruptionon failure.Tests added
ReadBlockTest.SizeOverflow-- verifies rejection of block handles with sizes nearSIZE_MAXReadBlockTest.TruncatedBlock-- verifies handling of blocks larger than the backing file