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LibCompress: Check for impossible back references in DeflateDecompressor

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This commit makes sure that we fail if an encoded lz77 back reference
references bytes that are outside our sliding window, instead of just
silently failing, which triggers an assertion down the line.
This commit is contained in:
Idan Horowitz 2021-03-17 17:42:08 +02:00 • committed by Andreas Kling
parent 9e6d0dd879
commit 071ee7c6f4
1 changed files with 4 additions and 0 deletions
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4
Userland/Libraries/LibCompress/Deflate.cpp
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@ -178,6 +178,10 @@ bool DeflateDecompressor::CompressedBlock::try_read_more()
for (size_t idx = 0; idx < length; ++idx) {
u8 byte = 0;
m_decompressor.m_output_stream.read({ &byte, sizeof(byte) }, distance);
if (m_decompressor.m_output_stream.handle_any_error()) {
m_decompressor.set_fatal_error();
return false; // a back reference was requested that was too far back (outside our current sliding window)
}
m_decompressor.m_output_stream << byte;
}