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compress/gzip: detect truncated streams

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Reader fails to detect truncated streams since calls to io.ReadFull
do not check if the error is io.EOF.

Change-Id: I052cd03161e43fec17e3d328106c40e17923e52b
Reviewed-on: https://go-review.googlesource.com/14832
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
This commit is contained in:
Joe Tsai 2015-09-22 02:14:28 -07:00 committed by Brad Fitzpatrick
parent 9deb940d24
commit b0a1f6462f
2 changed files with 48 additions and 0 deletions
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16
src/compress/gzip/gunzip.go
View File

@ -167,6 +167,9 @@ func (z *Reader) readString() (string, error) {
func (z *Reader) read2() (uint32, error) {
_, err := io.ReadFull(z.r, z.buf[0:2])
if err != nil {
if err == io.EOF {
err = io.ErrUnexpectedEOF
}
return 0, err
}
return uint32(z.buf[0]) | uint32(z.buf[1])<<8, nil
@ -175,6 +178,13 @@ func (z *Reader) read2() (uint32, error) {
func (z *Reader) readHeader(save bool) error {
_, err := io.ReadFull(z.r, z.buf[0:10])
if err != nil {
// RFC1952 section 2.2 says the following:
// A gzip file consists of a series of "members" (compressed data sets).
//
// Other than this, the specification does not clarify whether a
// "series" is defined as "one or more" or "zero or more". To err on the
// side of caution, Go interprets this to mean "zero or more".
// Thus, it is okay to return io.EOF here.
return err
}
if z.buf[0] != gzipID1 || z.buf[1] != gzipID2 || z.buf[2] != gzipDeflate {
@ -196,6 +206,9 @@ func (z *Reader) readHeader(save bool) error {
}
data := make([]byte, n)
if _, err = io.ReadFull(z.r, data); err != nil {
if err == io.EOF {
err = io.ErrUnexpectedEOF
}
return err
}
if save {
@ -260,6 +273,9 @@ func (z *Reader) Read(p []byte) (n int, err error) {
// Finished file; check checksum + size.
if _, err := io.ReadFull(z.r, z.buf[0:8]); err != nil {
if err == io.EOF {
err = io.ErrUnexpectedEOF
}
z.err = err
return 0, err
}

32
src/compress/gzip/gunzip_test.go
View File

@ -6,6 +6,7 @@ package gzip
import (
"bytes"
"compress/flate"
"io"
"io/ioutil"
"os"
@ -408,3 +409,34 @@ Found:
t.Fatalf("third reset: err=%v, want io.EOF", err)
}
}
func TestNilStream(t *testing.T) {
// Go liberally interprets RFC1952 section 2.2 to mean that a gzip file
// consist of zero or more members. Thus, we test that a nil stream is okay.
_, err := NewReader(bytes.NewReader(nil))
if err != io.EOF {
t.Fatalf("NewReader(nil) on empty stream: got %v, want &v", err, io.EOF)
}
}
func TestTruncatedStreams(t *testing.T) {
const data = "\x1f\x8b\b\x04\x00\tn\x88\x00\xff\a\x00foo bar\xcbH\xcd\xc9\xc9\xd7Q(\xcf/\xcaI\x01\x04:r\xab\xff\f\x00\x00\x00"
// Intentionally iterate starting with at least one byte in the stream.
for i := 1; i < len(data)-1; i++ {
r, err := NewReader(strings.NewReader(data[:i]))
if err != nil {
if err != io.ErrUnexpectedEOF {
t.Errorf("NewReader(%d) on truncated stream: got %v, want %v", i, err, io.ErrUnexpectedEOF)
}
continue
}
_, err = io.Copy(ioutil.Discard, r)
if ferr, ok := err.(*flate.ReadError); ok {
err = ferr.Err
}
if err != io.ErrUnexpectedEOF {
t.Errorf("io.Copy(%d) on truncated stream: got %v, want %v", i, err, io.ErrUnexpectedEOF)
}
}
}