Fix the crash due to inconsistent enc_write_ctx

- add error handling in ssl3_generate_key_block and ssl3_change_cipher_state

Fixes #2114

Reviewed-by: Rich Salz <rsalz@openssl.org>
Reviewed-by: Richard Levitte <levitte@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/2137)

diff --git a/ssl/s3_enc.c b/ssl/s3_enc.c
index fbc954d43c70c7be92089563a67c4e83d085345a..c2a769243c6326019228068355dcd24b2e780df4 100644 (file)
--- a/ssl/s3_enc.c
+++ b/ssl/s3_enc.c
@@ -177,32 +177,34 @@ static int ssl3_generate_key_block(SSL *s, unsigned char *km, int num)
     EVP_MD_CTX_init(&s1);
     for (i = 0; (int)i < num; i += MD5_DIGEST_LENGTH) {
         k++;
-        if (k > sizeof buf) {
+        if (k > sizeof(buf))
             /* bug: 'buf' is too small for this ciphersuite */
-            SSLerr(SSL_F_SSL3_GENERATE_KEY_BLOCK, ERR_R_INTERNAL_ERROR);
-            return 0;
-        }
+            goto err;
 
         for (j = 0; j < k; j++)
             buf[j] = c;
         c++;
-        EVP_DigestInit_ex(&s1, EVP_sha1(), NULL);
-        EVP_DigestUpdate(&s1, buf, k);
-        EVP_DigestUpdate(&s1, s->session->master_key,
-                         s->session->master_key_length);
-        EVP_DigestUpdate(&s1, s->s3->server_random, SSL3_RANDOM_SIZE);
-        EVP_DigestUpdate(&s1, s->s3->client_random, SSL3_RANDOM_SIZE);
-        EVP_DigestFinal_ex(&s1, smd, NULL);
-
-        EVP_DigestInit_ex(&m5, EVP_md5(), NULL);
-        EVP_DigestUpdate(&m5, s->session->master_key,
-                         s->session->master_key_length);
-        EVP_DigestUpdate(&m5, smd, SHA_DIGEST_LENGTH);
+        if (!EVP_DigestInit_ex(&s1, EVP_sha1(), NULL) ||
+            !EVP_DigestUpdate(&s1, buf, k) ||
+            !EVP_DigestUpdate(&s1, s->session->master_key,
+                              s->session->master_key_length) ||
+            !EVP_DigestUpdate(&s1, s->s3->server_random, SSL3_RANDOM_SIZE) ||
+            !EVP_DigestUpdate(&s1, s->s3->client_random, SSL3_RANDOM_SIZE) ||
+            !EVP_DigestFinal_ex(&s1, smd, NULL))
+            goto err2;
+
+        if (!EVP_DigestInit_ex(&m5, EVP_md5(), NULL) ||
+            !EVP_DigestUpdate(&m5, s->session->master_key,
+                              s->session->master_key_length) ||
+            !EVP_DigestUpdate(&m5, smd, SHA_DIGEST_LENGTH))
+            goto err2;
         if ((int)(i + MD5_DIGEST_LENGTH) > num) {
-            EVP_DigestFinal_ex(&m5, smd, NULL);
+            if (!EVP_DigestFinal_ex(&m5, smd, NULL))
+                goto err2;
             memcpy(km, smd, (num - i));
         } else
-            EVP_DigestFinal_ex(&m5, km, NULL);
+            if (!EVP_DigestFinal_ex(&m5, km, NULL))
+                goto err2;
 
         km += MD5_DIGEST_LENGTH;
     }
@@ -210,6 +212,12 @@ static int ssl3_generate_key_block(SSL *s, unsigned char *km, int num)
     EVP_MD_CTX_cleanup(&m5);
     EVP_MD_CTX_cleanup(&s1);
     return 1;
+ err:
+    SSLerr(SSL_F_SSL3_GENERATE_KEY_BLOCK, ERR_R_INTERNAL_ERROR);
+ err2:
+    EVP_MD_CTX_cleanup(&m5);
+    EVP_MD_CTX_cleanup(&s1);
+    return 0;
 }
 
 int ssl3_change_cipher_state(SSL *s, int which)
@@ -360,25 +368,33 @@ int ssl3_change_cipher_state(SSL *s, int which)
          * In here I set both the read and write key/iv to the same value
          * since only the correct one will be used :-).
          */
-        EVP_DigestInit_ex(&md, EVP_md5(), NULL);
-        EVP_DigestUpdate(&md, key, j);
-        EVP_DigestUpdate(&md, er1, SSL3_RANDOM_SIZE);
-        EVP_DigestUpdate(&md, er2, SSL3_RANDOM_SIZE);
-        EVP_DigestFinal_ex(&md, &(exp_key[0]), NULL);
+        if (!EVP_DigestInit_ex(&md, EVP_md5(), NULL) ||
+            !EVP_DigestUpdate(&md, key, j) ||
+            !EVP_DigestUpdate(&md, er1, SSL3_RANDOM_SIZE) ||
+            !EVP_DigestUpdate(&md, er2, SSL3_RANDOM_SIZE) ||
+            !EVP_DigestFinal_ex(&md, &(exp_key[0]), NULL)) {
+            EVP_MD_CTX_cleanup(&md);
+            goto err2;
+        }
         key = &(exp_key[0]);
 
         if (k > 0) {
-            EVP_DigestInit_ex(&md, EVP_md5(), NULL);
-            EVP_DigestUpdate(&md, er1, SSL3_RANDOM_SIZE);
-            EVP_DigestUpdate(&md, er2, SSL3_RANDOM_SIZE);
-            EVP_DigestFinal_ex(&md, &(exp_iv[0]), NULL);
+            if (!EVP_DigestInit_ex(&md, EVP_md5(), NULL) ||
+                !EVP_DigestUpdate(&md, er1, SSL3_RANDOM_SIZE) ||
+                !EVP_DigestUpdate(&md, er2, SSL3_RANDOM_SIZE) ||
+                !EVP_DigestFinal_ex(&md, &(exp_iv[0]), NULL)) {
+                EVP_MD_CTX_cleanup(&md);
+                goto err2;
+            }
             iv = &(exp_iv[0]);
         }
     }
+    EVP_MD_CTX_cleanup(&md);
 
     s->session->key_arg_length = 0;
 
-    EVP_CipherInit_ex(dd, c, NULL, key, iv, (which & SSL3_CC_WRITE));
+    if (!EVP_CipherInit_ex(dd, c, NULL, key, iv, (which & SSL3_CC_WRITE)))
+        goto err2;
 
 #ifdef OPENSSL_SSL_TRACE_CRYPTO
     if (s->msg_callback) {
@@ -399,7 +415,6 @@ int ssl3_change_cipher_state(SSL *s, int which)
 
     OPENSSL_cleanse(&(exp_key[0]), sizeof(exp_key));
     OPENSSL_cleanse(&(exp_iv[0]), sizeof(exp_iv));
-    EVP_MD_CTX_cleanup(&md);
     return (1);
  err:
     SSLerr(SSL_F_SSL3_CHANGE_CIPHER_STATE, ERR_R_MALLOC_FAILURE);
@@ -903,7 +918,7 @@ int ssl3_generate_master_secret(SSL *s, unsigned char *out, unsigned char *p,
                         s, s->msg_callback_arg);
     }
 #endif
-    OPENSSL_cleanse(buf, sizeof buf);
+    OPENSSL_cleanse(buf, sizeof(buf));
     return (ret);
 }