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std.compress.zstandard: validate skippable frame size

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This commit is contained in:
dweiller 2023-02-06 13:20:23 +11:00
parent 98bbd959b0
commit 2134769436
1 changed files with 30 additions and 14 deletions
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44
lib/std/compress/zstandard/decompress.zig
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@ -107,19 +107,27 @@ pub fn decodeAlloc(
/// - `error.UnusedBitSet` if the unused bit of the frame header is set
/// - `error.EndOfStream` if `src` does not contain a complete frame
/// - an error in `block.Error` if there are errors decoding a block
/// - `error.SkippableSizeTooLarge` if the frame is skippable and reports a
/// size greater than `src.len`
pub fn decodeFrame(
dest: []u8,
src: []const u8,
verify_checksum: bool,
) !ReadWriteCount {
var fbs = std.io.fixedBufferStream(src);
return switch (try decodeFrameType(fbs.reader())) {
.zstandard => decodeZstandardFrame(dest, src, verify_checksum),
.skippable => ReadWriteCount{
.read_count = try fbs.reader().readIntLittle(u32) + 8,
.write_count = 0,
switch (try decodeFrameType(fbs.reader())) {
.zstandard => return decodeZstandardFrame(dest, src, verify_checksum),
.skippable => {
const content_size = try fbs.reader().readIntLittle(u32);
if (content_size > std.math.maxInt(usize) - 8) return error.SkippableSizeTooLarge;
const read_count = @as(usize, content_size) + 8;
if (read_count > src.len) return error.SkippableSizeTooLarge;
return ReadWriteCount{
.read_count = read_count,
.write_count = 0,
};
},
};
}
}
pub const DecodeResult = struct {
@ -150,6 +158,8 @@ pub const DecodedFrame = union(enum) {
/// - `error.EndOfStream` if `src` does not contain a complete frame
/// - `error.OutOfMemory` if `allocator` cannot allocate enough memory
/// - an error in `block.Error` if there are errors decoding a block
/// - `error.SkippableSizeTooLarge` if the frame is skippable and reports a
/// size greater than `src.len`
pub fn decodeFrameAlloc(
allocator: Allocator,
src: []const u8,
@ -159,17 +169,23 @@ pub fn decodeFrameAlloc(
var fbs = std.io.fixedBufferStream(src);
const reader = fbs.reader();
const magic = try reader.readIntLittle(u32);
return switch (try frameType(magic)) {
.zstandard => .{
switch (try frameType(magic)) {
.zstandard => return .{
.zstandard = try decodeZstandardFrameAlloc(allocator, src, verify_checksum, window_size_max),
},
.skippable => .{
.skippable = .{
.magic_number = magic,
.frame_size = try reader.readIntLittle(u32),
},
.skippable => {
const content_size = try fbs.reader().readIntLittle(u32);
if (content_size > std.math.maxInt(usize) - 8) return error.SkippableSizeTooLarge;
const read_count = @as(usize, content_size) + 8;
if (read_count > src.len) return error.SkippableSizeTooLarge;
return .{
.skippable = .{
.magic_number = magic,
.frame_size = content_size,
},
};
},
};
}
}
/// Returns the frame checksum corresponding to the data fed into `hasher`