Fix AES handling to accept NULL/0 input

src/wp_aes_block.c

@@ -693,7 +693,9 @@ static int wp_aes_block_cipher(wp_AesBlockCtx* ctx, unsigned char* out,
     if (ok && (outSize < inLen)) {
         ok = 0;
     }
-    if (ok && !wp_aes_block_doit(ctx, out, in, inLen)) {
+    /* NULL in, NULL out, 0 len is OK */
+    if (ok && (out != NULL && in != NULL && inLen != 0) &&
+            !wp_aes_block_doit(ctx, out, in, inLen)) {
         ok = 0;
     }
     if (ok) {

src/wp_aes_stream.c

@@ -477,7 +477,9 @@ static int wp_aes_stream_cipher(wp_AesStreamCtx* ctx, unsigned char* out,
     if (ok && (outSize < inLen)) {
         ok = 0;
     }
-    if (ok && (!wp_aes_stream_doit(ctx, out, in, inLen))) {
+    /* NULL in, NULL out, 0 len is OK */
+    if (ok && (in != NULL && out != NULL && inLen != 0) &&
+              (!wp_aes_stream_doit(ctx, out, in, inLen))) {
         ok = 0;
     }
 

test/test_cipher.c

@@ -344,6 +344,92 @@ static int test_stream_enc_dec(void *data, const char *cipher, int keyLen,
     return err;
 }
 
+static int test_cipher_null_zero_ex(void *data, const char *cipher, int keyLen,
+    int ivLen)
+{
+    int err = 0;
+    unsigned char msg[16] = "Test pattern";
+    unsigned char key[32];
+    unsigned char iv[16];
+    unsigned char enc[sizeof(msg) + 16];
+    EVP_CIPHER *ocipher;
+    EVP_CIPHER *wcipher;
+    EVP_CIPHER_CTX *ctx;
+
+    (void)data;
+
+    ocipher = EVP_CIPHER_fetch(osslLibCtx, cipher, "");
+    wcipher = EVP_CIPHER_fetch(wpLibCtx, cipher, "");
+
+    if (RAND_bytes(key, keyLen) != 1) {
+        err = 1;
+    }
+    if (err == 0) {
+        if (RAND_bytes(iv, ivLen) != 1) {
+            err = 1;
+        }
+    }
+
+    /* Test that a final call with NULL/NULL/0 yields the correct return
+     * value, flow mimics that of libssh2 */
+    err = (ctx = EVP_CIPHER_CTX_new()) == NULL;
+    if (err == 0) {
+       err = EVP_CipherInit(ctx, ocipher, key, iv, 1) != 1;
+    }
+    if (err == 0) {
+        err = EVP_Cipher(ctx, enc, msg, sizeof(msg)) <= 0;
+    }
+    /* Return is 0, not negative value for NULL/NULL/0 input */
+    if (err == 0) {
+        err = EVP_Cipher(ctx, NULL, NULL, 0) != 0;
+    }
+    EVP_CIPHER_CTX_free(ctx);
+
+    err = (ctx = EVP_CIPHER_CTX_new()) == NULL;
+    if (err == 0) {
+       err = EVP_CipherInit(ctx, wcipher, key, iv, 1) != 1;
+    }
+    if (err == 0) {
+        err = EVP_Cipher(ctx, enc, msg, sizeof(msg)) <= 0;
+    }
+    /* Return is 0, not negative value for NULL/NULL/0 input */
+    if (err == 0) {
+        err = EVP_Cipher(ctx, NULL, NULL, 0) != 0;
+    }
+    EVP_CIPHER_CTX_free(ctx);
+
+    EVP_CIPHER_free(wcipher);
+    EVP_CIPHER_free(ocipher);
+
+    return err;
+}
+
+int test_cipher_null_zero(void *data)
+{
+    int err = 0;
+
+#ifdef WP_HAVE_AESECB
+    err = test_cipher_null_zero_ex(data, "AES-256-ECB", 32, 16);
+#endif
+#ifdef WP_HAVE_AESCBC
+    if (err == 0) {
+        err = test_cipher_null_zero_ex(data, "AES-256-CBC", 32, 16);
+    }
+#endif
+#ifdef WP_HAVE_AESCTR
+    if (err == 0) {
+        err = test_cipher_null_zero_ex(data, "AES-256-CTR", 32, 16);
+    }
+#endif
+#ifdef WP_HAVE_AESCFB
+    if (err == 0) {
+        err = test_cipher_null_zero_ex(data, "AES-256-CFB", 32, 16);
+    }
+#endif
+
+    return err;
+}
+
 #endif /* WP_HAVE_DES3CBC || WP_HAVE_AESCBC */
 
 /******************************************************************************/

test/unit.c

@@ -129,6 +129,7 @@ TEST_CASE test_case[] = {
     TEST_DECL(test_aes192_cfb_stream, NULL),
     TEST_DECL(test_aes256_cfb_stream, NULL),
 #endif
+    TEST_DECL(test_cipher_null_zero, NULL),
 #ifdef WP_HAVE_AESGCM
     TEST_DECL(test_aes128_gcm, NULL),
     TEST_DECL(test_aes192_gcm, NULL),

test/unit.h

@@ -174,6 +174,8 @@ int test_aes256_cfb_stream(void *data);
 
 #endif
 
+int test_cipher_null_zero(void *data);
+
 #ifdef WP_HAVE_AESGCM
 
 int test_aes128_gcm(void *data);