1 files changed, 32 insertions, 14 deletions

diff --git a/ssl/statem/statem_srvr.c b/ssl/statem/statem_srvr.c
index c0c406d921..876b6a79e3 100644
--- a/ssl/statem/statem_srvr.c
+++ b/ssl/statem/statem_srvr.c
@@ -3233,11 +3233,9 @@ static int tls_process_cke_gost(SSL *s, PACKET *pkt)
     const unsigned char *start;
     size_t outlen = 32, inlen;
     unsigned long alg_a;
-    int Ttag, Tclass;
-    long Tlen;
-    size_t sess_key_len;
-    const unsigned char *data;
+    unsigned int asn1id, asn1len;
     int ret = 0;
+    PACKET encdata;
 
     /* Get our certificate private key */
     alg_a = s->s3->tmp.new_cipher->algorithm_auth;
@@ -3279,22 +3277,42 @@ static int tls_process_cke_gost(SSL *s, PACKET *pkt)
             ERR_clear_error();
     }
     /* Decrypt session key */
-    sess_key_len = PACKET_remaining(pkt);
-    if (!PACKET_get_bytes(pkt, &data, sess_key_len)) {
-        SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_TLS_PROCESS_CKE_GOST,
-                 ERR_R_INTERNAL_ERROR);
+    if (!PACKET_get_1(pkt, &asn1id)
+            || asn1id != (V_ASN1_SEQUENCE | V_ASN1_CONSTRUCTED)
+            || !PACKET_peek_1(pkt, &asn1len)) {
+        SSLfatal(s, SSL_AD_DECODE_ERROR, SSL_F_TLS_PROCESS_CKE_GOST,
+                 SSL_R_DECRYPTION_FAILED);
         goto err;
     }
-    /* TODO(size_t): Convert this function */
-    if (ASN1_get_object((const unsigned char **)&data, &Tlen, &Ttag,
-                        &Tclass, (long)sess_key_len) != V_ASN1_CONSTRUCTED
-        || Ttag != V_ASN1_SEQUENCE || Tclass != V_ASN1_UNIVERSAL) {
+    if (asn1len == 0x81) {
+        /*
+         * Long form length. Should only be one byte of length. Anything else
+         * isn't supported.
+         * We did a successful peek before so this shouldn't fail
+         */
+        if (!PACKET_forward(pkt, 1)) {
+            SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_TLS_PROCESS_CKE_GOST,
+                     SSL_R_DECRYPTION_FAILED);
+            goto err;
+        }
+    } else  if (asn1len >= 0x80) {
+        /*
+         * Indefinite length, or more than one long form length bytes. We don't
+         * support it
+         */
+        SSLfatal(s, SSL_AD_DECODE_ERROR, SSL_F_TLS_PROCESS_CKE_GOST,
+                 SSL_R_DECRYPTION_FAILED);
+        goto err;
+    } /* else short form length */
+
+    if (!PACKET_as_length_prefixed_1(pkt, &encdata)) {
         SSLfatal(s, SSL_AD_DECODE_ERROR, SSL_F_TLS_PROCESS_CKE_GOST,
                  SSL_R_DECRYPTION_FAILED);
         goto err;
     }
-    start = data;
-    inlen = Tlen;
+    inlen = PACKET_remaining(&encdata);
+    start = PACKET_data(&encdata);
+
     if (EVP_PKEY_decrypt(pkey_ctx, premaster_secret, &outlen, start,
                          inlen) <= 0) {
         SSLfatal(s, SSL_AD_DECODE_ERROR, SSL_F_TLS_PROCESS_CKE_GOST,