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[release-branch.go1.17] archive/zip: don't panic on (*Reader).Open
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Previously, opening a zip with (*Reader).Open could result in a panic if
the zip contained a file whose name was exclusively made up of slash
characters or ".." path elements.

Open could also panic if passed the empty string directly as an argument.

Now, any files in the zip whose name could not be made valid for
fs.FS.Open will be skipped, and no longer added to the fs.FS file list,
although they are still accessible through (*Reader).File.

Note that it was already the case that a file could be accessible from
(*Reader).Open with a name different from the one in (*Reader).File, as
the former is the cleaned name, while the latter is the original one.

Finally, made the actual panic site robust as a defense-in-depth measure.

Fixes CVE-2021-41772
Fixes golang#48252
Updates golang#48085

Co-authored-by: Filippo Valsorda <[email protected]>
Change-Id: I6271a3f2892e7746f52e213b8eba9a1bba974678
Reviewed-on: https://go-review.googlesource.com/c/go/+/349770
Run-TryBot: Filippo Valsorda <[email protected]>
Reviewed-by: Katie Hockman <[email protected]>
Reviewed-by: Filippo Valsorda <[email protected]>
Trust: Katie Hockman <[email protected]>
Trust: Julie Qiu <[email protected]>
(cherry picked from commit b246873)
Reviewed-on: https://go-review.googlesource.com/c/go/+/360859
Trust: Dmitri Shuralyov <[email protected]>
Run-TryBot: Dmitri Shuralyov <[email protected]>
TryBot-Result: Go Bot <[email protected]>
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@Jason7602 @FiloSottile @katiehockman
2 people authored and katiehockman committed Nov 3, 2021
1 parent f9cb33c commit b212ba6
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Showing 2 changed files with 136 additions and 2 deletions.
10 changes: 8 additions & 2 deletions src/archive/zip/reader.go
View file
Original file line number Diff line number Diff line change
Expand Up @@ -741,6 +741,9 @@ func (r *Reader) initFileList() {
for _, file := range r.File {
isDir := len(file.Name) > 0 && file.Name[len(file.Name)-1] == '/'
name := toValidName(file.Name)
if name == "" {
continue
}
for dir := path.Dir(name); dir != "."; dir = path.Dir(dir) {
dirs[dir] = true
}
Expand Down Expand Up @@ -782,8 +785,11 @@ func fileEntryLess(x, y string) bool {
func (r *Reader) Open(name string) (fs.File, error) {
r.initFileList()

if !fs.ValidPath(name) {
return nil, &fs.PathError{Op: "open", Path: name, Err: fs.ErrInvalid}
}
e := r.openLookup(name)
if e == nil || !fs.ValidPath(name) {
if e == nil {
return nil, &fs.PathError{Op: "open", Path: name, Err: fs.ErrNotExist}
}
if e.isDir {
Expand All @@ -797,7 +803,7 @@ func (r *Reader) Open(name string) (fs.File, error) {
}

func split(name string) (dir, elem string, isDir bool) {
if name[len(name)-1] == '/' {
if len(name) > 0 && name[len(name)-1] == '/' {
isDir = true
name = name[:len(name)-1]
}
Expand Down
128 changes: 128 additions & 0 deletions src/archive/zip/reader_test.go
View file
Original file line number Diff line number Diff line change
Expand Up @@ -13,6 +13,7 @@ import (
"io/fs"
"os"
"path/filepath"
"reflect"
"regexp"
"strings"
"testing"
Expand Down Expand Up @@ -1202,6 +1203,15 @@ func TestCVE202127919(t *testing.T) {
if err != nil {
t.Errorf("Error reading file: %v", err)
}
if len(r.File) != 1 {
t.Fatalf("No entries in the file list")
}
if r.File[0].Name != "../test.txt" {
t.Errorf("Unexpected entry name: %s", r.File[0].Name)
}
if _, err := r.File[0].Open(); err != nil {
t.Errorf("Error opening file: %v", err)
}
}

func TestReadDataDescriptor(t *testing.T) {
Expand Down Expand Up @@ -1402,3 +1412,121 @@ func TestCVE202139293(t *testing.T) {
t.Fatalf("unexpected error, got: %v, want: %v", err, ErrFormat)
}
}

func TestCVE202141772(t *testing.T) {
// Archive contains a file whose name is exclusively made up of '/', '\'
// characters, or "../", "..\" paths, which would previously cause a panic.
//
// Length Method Size Cmpr Date Time CRC-32 Name
// -------- ------ ------- ---- ---------- ----- -------- ----
// 0 Stored 0 0% 08-05-2021 18:32 00000000 /
// 0 Stored 0 0% 09-14-2021 12:59 00000000 //
// 0 Stored 0 0% 09-14-2021 12:59 00000000 \
// 11 Stored 11 0% 09-14-2021 13:04 0d4a1185 /test.txt
// -------- ------- --- -------
// 11 11 0% 4 files
data := []byte{
0x50, 0x4b, 0x03, 0x04, 0x0a, 0x00, 0x00, 0x08,
0x00, 0x00, 0x06, 0x94, 0x05, 0x53, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x01, 0x00, 0x00, 0x00, 0x2f, 0x50,
0x4b, 0x03, 0x04, 0x0a, 0x00, 0x00, 0x00, 0x00,
0x00, 0x78, 0x67, 0x2e, 0x53, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x02, 0x00, 0x00, 0x00, 0x2f, 0x2f, 0x50,
0x4b, 0x03, 0x04, 0x0a, 0x00, 0x00, 0x00, 0x00,
0x00, 0x78, 0x67, 0x2e, 0x53, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x01, 0x00, 0x00, 0x00, 0x5c, 0x50, 0x4b,
0x03, 0x04, 0x0a, 0x00, 0x00, 0x00, 0x00, 0x00,
0x91, 0x68, 0x2e, 0x53, 0x85, 0x11, 0x4a, 0x0d,
0x0b, 0x00, 0x00, 0x00, 0x0b, 0x00, 0x00, 0x00,
0x09, 0x00, 0x00, 0x00, 0x2f, 0x74, 0x65, 0x73,
0x74, 0x2e, 0x74, 0x78, 0x74, 0x68, 0x65, 0x6c,
0x6c, 0x6f, 0x20, 0x77, 0x6f, 0x72, 0x6c, 0x64,
0x50, 0x4b, 0x01, 0x02, 0x14, 0x03, 0x0a, 0x00,
0x00, 0x08, 0x00, 0x00, 0x06, 0x94, 0x05, 0x53,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x01, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x10, 0x00,
0xed, 0x41, 0x00, 0x00, 0x00, 0x00, 0x2f, 0x50,
0x4b, 0x01, 0x02, 0x3f, 0x00, 0x0a, 0x00, 0x00,
0x00, 0x00, 0x00, 0x78, 0x67, 0x2e, 0x53, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x02, 0x00, 0x24, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x20, 0x00, 0x00,
0x00, 0x1f, 0x00, 0x00, 0x00, 0x2f, 0x2f, 0x0a,
0x00, 0x20, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01,
0x00, 0x18, 0x00, 0x93, 0x98, 0x25, 0x57, 0x25,
0xa9, 0xd7, 0x01, 0x93, 0x98, 0x25, 0x57, 0x25,
0xa9, 0xd7, 0x01, 0x93, 0x98, 0x25, 0x57, 0x25,
0xa9, 0xd7, 0x01, 0x50, 0x4b, 0x01, 0x02, 0x3f,
0x00, 0x0a, 0x00, 0x00, 0x00, 0x00, 0x00, 0x78,
0x67, 0x2e, 0x53, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01,
0x00, 0x24, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x20, 0x00, 0x00, 0x00, 0x3f, 0x00, 0x00,
0x00, 0x5c, 0x0a, 0x00, 0x20, 0x00, 0x00, 0x00,
0x00, 0x00, 0x01, 0x00, 0x18, 0x00, 0x93, 0x98,
0x25, 0x57, 0x25, 0xa9, 0xd7, 0x01, 0x93, 0x98,
0x25, 0x57, 0x25, 0xa9, 0xd7, 0x01, 0x93, 0x98,
0x25, 0x57, 0x25, 0xa9, 0xd7, 0x01, 0x50, 0x4b,
0x01, 0x02, 0x3f, 0x00, 0x0a, 0x00, 0x00, 0x00,
0x00, 0x00, 0x91, 0x68, 0x2e, 0x53, 0x85, 0x11,
0x4a, 0x0d, 0x0b, 0x00, 0x00, 0x00, 0x0b, 0x00,
0x00, 0x00, 0x09, 0x00, 0x24, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x20, 0x00, 0x00, 0x00,
0x5e, 0x00, 0x00, 0x00, 0x2f, 0x74, 0x65, 0x73,
0x74, 0x2e, 0x74, 0x78, 0x74, 0x0a, 0x00, 0x20,
0x00, 0x00, 0x00, 0x00, 0x00, 0x01, 0x00, 0x18,
0x00, 0xa9, 0x80, 0x51, 0x01, 0x26, 0xa9, 0xd7,
0x01, 0x31, 0xd1, 0x57, 0x01, 0x26, 0xa9, 0xd7,
0x01, 0xdf, 0x48, 0x85, 0xf9, 0x25, 0xa9, 0xd7,
0x01, 0x50, 0x4b, 0x05, 0x06, 0x00, 0x00, 0x00,
0x00, 0x04, 0x00, 0x04, 0x00, 0x31, 0x01, 0x00,
0x00, 0x90, 0x00, 0x00, 0x00, 0x00, 0x00,
}
r, err := NewReader(bytes.NewReader([]byte(data)), int64(len(data)))
if err != nil {
t.Fatalf("Error reading the archive: %v", err)
}
entryNames := []string{`/`, `//`, `\`, `/test.txt`}
var names []string
for _, f := range r.File {
names = append(names, f.Name)
if _, err := f.Open(); err != nil {
t.Errorf("Error opening %q: %v", f.Name, err)
}
if _, err := r.Open(f.Name); err == nil {
t.Errorf("Opening %q with fs.FS API succeeded", f.Name)
}
}
if !reflect.DeepEqual(names, entryNames) {
t.Errorf("Unexpected file entries: %q", names)
}
if _, err := r.Open(""); err == nil {
t.Errorf("Opening %q with fs.FS API succeeded", "")
}
if _, err := r.Open("test.txt"); err != nil {
t.Errorf("Error opening %q with fs.FS API: %v", "test.txt", err)
}
dirEntries, err := fs.ReadDir(r, ".")
if err != nil {
t.Fatalf("Error reading the root directory: %v", err)
}
if len(dirEntries) != 1 || dirEntries[0].Name() != "test.txt" {
t.Errorf("Unexpected directory entries")
for _, dirEntry := range dirEntries {
_, err := r.Open(dirEntry.Name())
t.Logf("%q (Open error: %v)", dirEntry.Name(), err)
}
t.FailNow()
}
info, err := dirEntries[0].Info()
if err != nil {
t.Fatalf("Error reading info entry: %v", err)
}
if name := info.Name(); name != "test.txt" {
t.Errorf("Inconsistent name in info entry: %v", name)
}
}

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