archive/zip: verify number of File bytes read at EOF

Fixes #10957

Change-Id: I75fe25133dfcebd1682a8058b1c354ec894cc997
Reviewed-on: https://go-review.googlesource.com/10384
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: Andrew Gerrand <adg@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

Author: bradfitz

Diff for: src/archive/zip/reader.go

@@ -146,16 +146,22 @@ func (f *File) Open() (rc io.ReadCloser, err error) {
 	if f.hasDataDescriptor() {
 		desr = io.NewSectionReader(f.zipr, f.headerOffset+bodyOffset+size, dataDescriptorLen)
 	}
-	rc = &checksumReader{rc, crc32.NewIEEE(), f, desr, nil}
+	rc = &checksumReader{
+		rc:   rc,
+		hash: crc32.NewIEEE(),
+		f:    f,
+		desr: desr,
+	}
 	return
 }
 
 type checksumReader struct {
-	rc   io.ReadCloser
-	hash hash.Hash32
-	f    *File
-	desr io.Reader // if non-nil, where to read the data descriptor
-	err  error     // sticky error
+	rc    io.ReadCloser
+	hash  hash.Hash32
+	nread uint64 // number of bytes read so far
+	f     *File
+	desr  io.Reader // if non-nil, where to read the data descriptor
+	err   error     // sticky error
 }
 
 func (r *checksumReader) Read(b []byte) (n int, err error) {
@@ -164,10 +170,14 @@ func (r *checksumReader) Read(b []byte) (n int, err error) {
 	}
 	n, err = r.rc.Read(b)
 	r.hash.Write(b[:n])
+	r.nread += uint64(n)
 	if err == nil {
 		return
 	}
 	if err == io.EOF {
+		if r.nread != r.f.UncompressedSize64 {
+			return 0, io.ErrUnexpectedEOF
+		}
 		if r.desr != nil {
 			if err1 := readDataDescriptor(r.desr, r.f); err1 != nil {
 				err = err1

Diff for: src/archive/zip/reader_test.go

@@ -531,3 +531,45 @@ func TestIssue8186(t *testing.T) {
 		}
 	}
 }
+
+// Verify we return ErrUnexpectedEOF when length is short.
+func TestIssue10957(t *testing.T) {
+	data := []byte("PK\x03\x040000000PK\x01\x0200000" +
+		"0000000000000000000\x00" +
+		"\x00\x00\x00\x00\x00000000000000PK\x01" +
+		"\x020000000000000000000" +
+		"00000\v\x00\x00\x00\x00\x00000000000" +
+		"00000000000000PK\x01\x0200" +
+		"00000000000000000000" +
+		"00\v\x00\x00\x00\x00\x00000000000000" +
+		"00000000000PK\x01\x020000<" +
+		"0\x00\x0000000000000000\v\x00\v" +
+		"\x00\x00\x00\x00\x0000000000\x00\x00\x00\x00000" +
+		"00000000PK\x01\x0200000000" +
+		"0000000000000000\v\x00\x00\x00" +
+		"\x00\x0000PK\x05\x06000000\x05\x000000" +
+		"\v\x00\x00\x00\x00\x00")
+	z, err := NewReader(bytes.NewReader(data), int64(len(data)))
+	if err != nil {
+		if z != nil {
+			panic("non nil z")
+		}
+		return
+	}
+	for i, f := range z.File {
+		r, err := f.Open()
+		if err != nil {
+			continue
+		}
+		if f.UncompressedSize64 < 1e6 {
+			n, err := io.Copy(ioutil.Discard, r)
+			if i == 3 && err != io.ErrUnexpectedEOF {
+				t.Errorf("File[3] error = %v; want io.ErrUnexpectedEOF", err)
+			}
+			if err == nil && uint64(n) != f.UncompressedSize64 {
+				t.Errorf("file %d: bad size: copied=%d; want=%d", i, n, f.UncompressedSize64)
+			}
+		}
+		r.Close()
+	}
+}