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LibCompress: Implement correct validation of last filters
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parent
786e654dfd
commit
25642dfe87
Notes:
sideshowbarker
2024-07-17 05:23:40 +09:00
Author: https://github.com/timschumi Commit: https://github.com/SerenityOS/serenity/commit/25642dfe87 Pull-request: https://github.com/SerenityOS/serenity/pull/21552 Reviewed-by: https://github.com/gmta ✅
@ -1864,9 +1864,6 @@ TEST_CASE(xz_utils_unsupported_filter_flags_2)
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auto stream = MUST(try_make<FixedMemoryStream>(compressed));
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auto decompressor = MUST(Compress::XzDecompressor::create(move(stream)));
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// TODO: We don't yet check whether the filter chain satisfies the "can't be the last filter"
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// requirement. We just happen to get the result right because we try to uncompress the
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// test case and fail.
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auto buffer_or_error = decompressor->read_until_eof(PAGE_SIZE);
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EXPECT(buffer_or_error.is_error());
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}
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@ -121,7 +121,7 @@ u32 XzStreamFooter::backward_size() const
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return (encoded_backward_size + 1) * 4;
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}
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u8 XzBlockFlags::number_of_filters() const
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size_t XzBlockFlags::number_of_filters() const
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{
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// 3.1.2. Block Flags:
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// "Bit(s) Mask Description
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@ -380,6 +380,7 @@ ErrorOr<void> XzDecompressor::load_next_block(u8 encoded_block_header_size)
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struct FilterEntry {
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u64 id;
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ByteBuffer properties;
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bool last;
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};
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Vector<FilterEntry, 4> filters;
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@ -387,6 +388,8 @@ ErrorOr<void> XzDecompressor::load_next_block(u8 encoded_block_header_size)
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// "The number of Filter Flags fields is stored in the Block Flags
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// field (see Section 3.1.2)."
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for (size_t i = 0; i < flags.number_of_filters(); i++) {
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auto last = (i == flags.number_of_filters() - 1);
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// "The format of each Filter Flags field is as follows:
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// Both Filter ID and Size of Properties are stored using the
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// encoding described in Section 1.2."
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@ -397,12 +400,15 @@ ErrorOr<void> XzDecompressor::load_next_block(u8 encoded_block_header_size)
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auto filter_properties = TRY(ByteBuffer::create_uninitialized(size_of_properties));
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TRY(header_stream.read_until_filled(filter_properties));
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filters.empend(filter_id, move(filter_properties));
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filters.empend(filter_id, move(filter_properties), last);
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}
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for (auto& filter : filters.in_reverse()) {
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// 5.3.1. LZMA2
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if (filter.id == 0x21) {
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if (!filter.last)
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return Error::from_string_literal("XZ LZMA2 filter can only be the last filter");
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if (filter.properties.size() < sizeof(XzFilterLzma2Properties))
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return Error::from_string_literal("XZ LZMA2 filter has a smaller-than-needed properties size");
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@ -415,6 +421,9 @@ ErrorOr<void> XzDecompressor::load_next_block(u8 encoded_block_header_size)
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// 5.3.3. Delta
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if (filter.id == 0x03) {
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if (filter.last)
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return Error::from_string_literal("XZ Delta filter can only be a non-last filter");
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if (filter.properties.size() < sizeof(XzFilterDeltaProperties))
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return Error::from_string_literal("XZ Delta filter has a smaller-than-needed properties size");
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@ -85,7 +85,7 @@ struct [[gnu::packed]] XzBlockFlags {
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bool compressed_size_present : 1;
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bool uncompressed_size_present : 1;
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u8 number_of_filters() const;
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size_t number_of_filters() const;
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};
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static_assert(sizeof(XzBlockFlags) == 1);
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