archive/zip: don't panic on (*Reader).Open
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 #48085
Co-authored-by: Filippo Valsorda <filippo@golang.org>
Change-Id: I6271a3f2892e7746f52e213b8eba9a1bba974678
Reviewed-on: https://go-review.googlesource.com/c/go/+/349770
Run-TryBot: Filippo Valsorda <filippo@golang.org>
Reviewed-by: Katie Hockman <katie@golang.org>
Reviewed-by: Filippo Valsorda <filippo@golang.org>
Trust: Katie Hockman <katie@golang.org>
Trust: Julie Qiu <julie@golang.org>
diff --git a/src/archive/zip/reader.go b/src/archive/zip/reader.go
index c91a8d0..e40a2c6 100644
--- a/src/archive/zip/reader.go
+++ b/src/archive/zip/reader.go
@@ -741,6 +741,9 @@
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
}
@@ -782,8 +785,11 @@
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 {
@@ -797,7 +803,7 @@
}
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]
}
diff --git a/src/archive/zip/reader_test.go b/src/archive/zip/reader_test.go
index afb03ac..a549153 100644
--- a/src/archive/zip/reader_test.go
+++ b/src/archive/zip/reader_test.go
@@ -13,6 +13,7 @@
"io/fs"
"os"
"path/filepath"
+ "reflect"
"regexp"
"strings"
"testing"
@@ -1202,6 +1203,15 @@
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) {
@@ -1402,3 +1412,121 @@
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)
+ }
+}
