archive/zip: fix panic in Reader.Open

When operating on a Zip file that contains a file prefixed with "../",
Open(...) would cause a panic in toValidName when attempting to strip
the prefixed path components.

Fixes CVE-2021-27919
Fixes #44916

Change-Id: Ic755d8126cb0897e2cbbdacf572439c38dde7b35
Reviewed-on: https://team-review.git.corp.google.com/c/golang/go-private/+/1004761
Reviewed-by: Filippo Valsorda <valsorda@google.com>
Reviewed-by: Russ Cox <rsc@google.com>
Reviewed-by: Katie Hockman <katiehockman@google.com>
Reviewed-on: https://go-review.googlesource.com/c/go/+/300489
Trust: Katie Hockman <katie@golang.org>
Run-TryBot: Katie Hockman <katie@golang.org>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Alexander Rakoczy <alex@golang.org>
Reviewed-by: Filippo Valsorda <filippo@golang.org>

diff --git a/src/archive/zip/reader.go b/src/archive/zip/reader.go
index 8b4e77875fb3e69c93406372e17d94bb3f1b7d91..c288ad965bc92cd4477e8c9da1eb8033d84c3cbe 100644 (file)
--- a/src/archive/zip/reader.go
+++ b/src/archive/zip/reader.go
@@ -664,7 +664,7 @@ func toValidName(name string) string {
        if strings.HasPrefix(p, "/") {
                p = p[len("/"):]
        }
-       for strings.HasPrefix(name, "../") {
+       for strings.HasPrefix(p, "../") {
                p = p[len("../"):]
        }
        return p

diff --git a/src/archive/zip/reader_test.go b/src/archive/zip/reader_test.go
index 34e96f7da43c2a79e26f2f2527a78f9265914163..5faf1f49b51e7b8e4cd25fbb34dfd32d46ed03bd 100644 (file)
--- a/src/archive/zip/reader_test.go
+++ b/src/archive/zip/reader_test.go
@@ -1081,3 +1081,38 @@ func TestFS(t *testing.T) {
                t.Fatal(err)
        }
 }
+
+func TestCVE202127919(t *testing.T) {
+       // Archive containing only the file "../test.txt"
+       data := []byte{
+               0x50, 0x4b, 0x03, 0x04, 0x14, 0x00, 0x08, 0x00,
+               0x08, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+               0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+               0x00, 0x00, 0x0b, 0x00, 0x00, 0x00, 0x2e, 0x2e,
+               0x2f, 0x74, 0x65, 0x73, 0x74, 0x2e, 0x74, 0x78,
+               0x74, 0x0a, 0xc9, 0xc8, 0x2c, 0x56, 0xc8, 0x2c,
+               0x56, 0x48, 0x54, 0x28, 0x49, 0x2d, 0x2e, 0x51,
+               0x28, 0x49, 0xad, 0x28, 0x51, 0x48, 0xcb, 0xcc,
+               0x49, 0xd5, 0xe3, 0x02, 0x04, 0x00, 0x00, 0xff,
+               0xff, 0x50, 0x4b, 0x07, 0x08, 0xc0, 0xd7, 0xed,
+               0xc3, 0x20, 0x00, 0x00, 0x00, 0x1a, 0x00, 0x00,
+               0x00, 0x50, 0x4b, 0x01, 0x02, 0x14, 0x00, 0x14,
+               0x00, 0x08, 0x00, 0x08, 0x00, 0x00, 0x00, 0x00,
+               0x00, 0xc0, 0xd7, 0xed, 0xc3, 0x20, 0x00, 0x00,
+               0x00, 0x1a, 0x00, 0x00, 0x00, 0x0b, 0x00, 0x00,
+               0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+               0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x2e,
+               0x2e, 0x2f, 0x74, 0x65, 0x73, 0x74, 0x2e, 0x74,
+               0x78, 0x74, 0x50, 0x4b, 0x05, 0x06, 0x00, 0x00,
+               0x00, 0x00, 0x01, 0x00, 0x01, 0x00, 0x39, 0x00,
+               0x00, 0x00, 0x59, 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)
+       }
+       _, err = r.Open("test.txt")
+       if err != nil {
+               t.Errorf("Error reading file: %v", err)
+       }
+}