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leveldb: Check slice length in Footer::DecodeFrom()

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Without this check decoding the footer in Table::Open() can read
uninitialized bytes from a buffer allocated on the stack if the file
was unexpectedly short.

In practice this is probably fine since this function validates a magic
number but MSan complains about branching on uninitialized data.

PiperOrigin-RevId: 525271012
This commit is contained in:
leveldb Team 2023-04-18 22:38:59 +00:00 committed by Austin Sullivan
parent c61238dcf3
commit 068d5ee1a3
1 changed files with 4 additions and 0 deletions
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4
table/format.cc
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@ -41,6 +41,10 @@ void Footer::EncodeTo(std::string* dst) const {
} }
Status Footer::DecodeFrom(Slice* input) { Status Footer::DecodeFrom(Slice* input) {
if (input->size() < kEncodedLength) {
return Status::Corruption("not an sstable (footer too short)");
}
const char* magic_ptr = input->data() + kEncodedLength - 8; const char* magic_ptr = input->data() + kEncodedLength - 8;
const uint32_t magic_lo = DecodeFixed32(magic_ptr); const uint32_t magic_lo = DecodeFixed32(magic_ptr);
const uint32_t magic_hi = DecodeFixed32(magic_ptr + 4); const uint32_t magic_hi = DecodeFixed32(magic_ptr + 4);