Commit e252e6c696192729e576fffbd26991bd4b19e434 | zig

author	Andrew Kelley <andrew@ziglang.org> 2025-08-14 16:08:06-07:00
committer	GitHub <noreply@github.com> 2025-08-14 16:08:06-07:00
log	e252e6c696192729e576fffbd26991bd4b19e434
tree	481c8137999a5a650066e2d5229b21b69cf23e76
parent	2761cc8be0ef89772a41cb0aaf512ac463aa5c23
parent	353cf1f671b9127e7f425aaf3dcba655117ee45b
signature	Signed by PGP key B5690EEEBB952194

zstd.Decompress: Treat a partial magic number as a failure

2 files changed, 18 insertions(+), 3 deletions(-)

lib/std/compress/zstd.zig+6

...	...	@@ -121,6 +121,12 @@ test Decompress {
121	121	try testExpectDecompress(uncompressed, compressed19);
122	122	}
123	123
	124	test "partial magic number" {
	125	const input_raw =
	126	"\x28\xb5\x2f"; // 3 bytes of the 4-byte zstandard frame magic number
	127	try testExpectDecompressError(error.BadMagic, input_raw);
	128	}
	129
124	130	test "zero sized raw block" {
125	131	const input_raw =
126	132	"\x28\xb5\x2f\xfd" ++ // zstandard frame magic number

lib/std/compress/zstd/Decompress.zig+12-3

...	...	@@ -17,7 +17,6 @@ const State = union(enum) {
17	17	new_frame,
18	18	in_frame: InFrame,
19	19	skipping_frame: usize,
20		end,
21	20
22	21	const InFrame = struct {
23	22	frame: Frame,
...	...	@@ -158,7 +157,18 @@ fn stream(r: Reader, w: Writer, limit: Limit) Reader.StreamError!usize {
158	157
159	158	switch (d.state) {
160	159	.new_frame => {
161		// Allow error.EndOfStream only on the frame magic.
	160	// Only return EndOfStream when there are exactly 0 bytes remaining on the
	161	// frame magic. Any partial magic bytes should be considered a failure.
	162	in.fill(@sizeOf(Frame.Magic)) catch \|err\| switch (err) {
	163	error.EndOfStream => {
	164	if (in.bufferedLen() != 0) {
	165	d.err = error.BadMagic;
	166	return error.ReadFailed;
	167	}
	168	return err;
	169	},
	170	else => \|e\| return e,
	171	};
162	172	const magic = try in.takeEnumNonexhaustive(Frame.Magic, .little);
163	173	initFrame(d, w.buffer.len, magic) catch \|err\| {
164	174	d.err = err;
...	...	@@ -192,7 +202,6 @@ fn stream(r: Reader, w: Writer, limit: Limit) Reader.StreamError!usize {
192	202	if (remaining.* == 0) d.state = .new_frame;
193	203	return 0;
194	204	},
195		.end => return error.EndOfStream,
196	205	}
197	206	}
198	207