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std.compress.zstandard: fix crashes

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This commit is contained in:
dweiller 2023-02-03 15:35:30 +11:00
parent 596a97fb55
commit 1c509f483a
2 changed files with 10 additions and 6 deletions
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2
lib/std/compress/zstandard/decode/block.zig
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@ -981,6 +981,8 @@ fn decodeStreams(size_format: u2, stream_data: []const u8) !LiteralsSection.Stre
const stream_3_start = stream_2_start + stream_2_length;
const stream_4_start = stream_3_start + stream_3_length;
if (stream_data.len < stream_4_start) return error.MalformedLiteralsSection;
return .{ .four = .{
stream_data[stream_1_start .. stream_1_start + stream_1_length],
stream_data[stream_2_start .. stream_2_start + stream_2_length],

14
lib/std/compress/zstandard/decode/huffman.zig
View File

@ -59,7 +59,7 @@ fn assignWeights(huff_bits: *readers.ReverseBitReader, accuracy_log: usize, entr
var even_state: u32 = huff_bits.readBitsNoEof(u32, accuracy_log) catch return error.MalformedHuffmanTree;
var odd_state: u32 = huff_bits.readBitsNoEof(u32, accuracy_log) catch return error.MalformedHuffmanTree;
while (i < 255) {
while (i < 254) {
const even_data = entries[even_state];
var read_bits: usize = 0;
const even_bits = huff_bits.readBits(u32, even_data.bits, &read_bits) catch unreachable;
@ -78,7 +78,7 @@ fn assignWeights(huff_bits: *readers.ReverseBitReader, accuracy_log: usize, entr
weights[i] = std.math.cast(u4, odd_data.symbol) orelse return error.MalformedHuffmanTree;
i += 1;
if (read_bits < odd_data.bits) {
if (i == 256) return error.MalformedHuffmanTree;
if (i == 255) return error.MalformedHuffmanTree;
weights[i] = std.math.cast(u4, entries[even_state].symbol) orelse return error.MalformedHuffmanTree;
i += 1;
break;
@ -147,16 +147,18 @@ fn assignSymbols(weight_sorted_prefixed_symbols: []LiteralsSection.HuffmanTree.P
}
fn buildHuffmanTree(weights: *[256]u4, symbol_count: usize) error{MalformedHuffmanTree}!LiteralsSection.HuffmanTree {
var weight_power_sum: u16 = 0;
var weight_power_sum_big: u32 = 0;
for (weights[0 .. symbol_count - 1]) |value| {
if (value > 0) {
weight_power_sum += @as(u16, 1) << (value - 1);
weight_power_sum_big += @as(u16, 1) << (value - 1);
}
}
if (weight_power_sum >= 1 << 11) return error.MalformedHuffmanTree;
if (weight_power_sum_big >= 1 << 11) return error.MalformedHuffmanTree;
const weight_power_sum = @intCast(u16, weight_power_sum_big);
// advance to next power of two (even if weight_power_sum is a power of 2)
const max_number_of_bits = std.math.log2_int(u16, weight_power_sum) + 1;
// TODO: is it valid to have weight_power_sum == 0?
const max_number_of_bits = if (weight_power_sum == 0) 1 else std.math.log2_int(u16, weight_power_sum) + 1;
const next_power_of_two = @as(u16, 1) << max_number_of_bits;
weights[symbol_count - 1] = std.math.log2_int(u16, next_power_of_two - weight_power_sum) + 1;