Commit 61f1a38b authored by Michael Munday's avatar Michael Munday

crypto/{aes,cipher}: fix panic in CBC on s390x when src length is 0

Adds a test to check that block cipher modes accept a zero-length
input.

Fixes #17435.

Change-Id: Ie093c4cdff756b5c2dcb79342e167b3de5622389
Reviewed-on: https://go-review.googlesource.com/31070
Run-TryBot: Michael Munday <munday@ca.ibm.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: default avatarBrad Fitzpatrick <bradfitz@golang.org>
parent 714318be
......@@ -48,7 +48,9 @@ func (x *cbc) CryptBlocks(dst, src []byte) {
if len(dst) < len(src) {
panic("crypto/cipher: output smaller than input")
}
if len(src) > 0 {
cryptBlocksChain(x.c, &x.iv[0], &x.b.key[0], &dst[0], &src[0], len(src))
}
}
func (x *cbc) SetIV(iv []byte) {
......
......@@ -5,8 +5,10 @@
package cipher_test
import (
"bytes"
"crypto/aes"
"crypto/cipher"
"crypto/des"
"testing"
)
......@@ -34,3 +36,55 @@ func mustPanic(t *testing.T, msg string, f func()) {
}()
f()
}
func TestEmptyPlaintext(t *testing.T) {
var key [16]byte
a, err := aes.NewCipher(key[:16])
if err != nil {
t.Fatal(err)
}
d, err := des.NewCipher(key[:8])
if err != nil {
t.Fatal(err)
}
s := 16
pt := make([]byte, s)
ct := make([]byte, s)
for i := 0; i < 16; i++ {
pt[i], ct[i] = byte(i), byte(i)
}
assertEqual := func(name string, got, want []byte) {
if !bytes.Equal(got, want) {
t.Fatalf("%s: got %v, want %v", name, got, want)
}
}
for _, b := range []cipher.Block{a, d} {
iv := make([]byte, b.BlockSize())
cbce := cipher.NewCBCEncrypter(b, iv)
cbce.CryptBlocks(ct, pt[:0])
assertEqual("CBC encrypt", ct, pt)
cbcd := cipher.NewCBCDecrypter(b, iv)
cbcd.CryptBlocks(ct, pt[:0])
assertEqual("CBC decrypt", ct, pt)
cfbe := cipher.NewCFBEncrypter(b, iv)
cfbe.XORKeyStream(ct, pt[:0])
assertEqual("CFB encrypt", ct, pt)
cfbd := cipher.NewCFBDecrypter(b, iv)
cfbd.XORKeyStream(ct, pt[:0])
assertEqual("CFB decrypt", ct, pt)
ctr := cipher.NewCTR(b, iv)
ctr.XORKeyStream(ct, pt[:0])
assertEqual("CTR", ct, pt)
ofb := cipher.NewOFB(b, iv)
ofb.XORKeyStream(ct, pt[:0])
assertEqual("OFB", ct, pt)
}
}
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