Fix race condition in NewSessionTicket

If a NewSessionTicket is received by a multi-threaded client when
attempting to reuse a previous ticket then a race condition can occur
potentially leading to a double free of the ticket data.

CVE-2015-1791

This also fixes RT#3808 where a session ID is changed for a session already
in the client session cache. Since the session ID is the key to the cache
this breaks the cache access.

Parts of this patch were inspired by this Akamai change:
https://github.com/akamai/openssl/commit/c0bf69a791239ceec64509f9f19fcafb2461b0d3

Reviewed-by: Rich Salz <rsalz@openssl.org>
(cherry picked from commit 27c76b9b8010b536687318739c6f631ce4194688)

Conflicts:
	ssl/ssl.h
	ssl/ssl_err.c

1 files changed, 123 insertions, 0 deletions

diff --git a/ssl/ssl_sess.c b/ssl/ssl_sess.c
index eb7936b4e1..e673f9c621 100644
--- a/ssl/ssl_sess.c
+++ b/ssl/ssl_sess.c
@@ -227,6 +227,129 @@ SSL_SESSION *SSL_SESSION_new(void)
     return (ss);
 }
 
+/*
+ * Create a new SSL_SESSION and duplicate the contents of |src| into it. If
+ * ticket == 0 then no ticket information is duplicated, otherwise it is.
+ */
+SSL_SESSION *ssl_session_dup(SSL_SESSION *src, int ticket)
+{
+    SSL_SESSION *dest;
+
+    dest = OPENSSL_malloc(sizeof(*src));
+    if (dest == NULL) {
+        goto err;
+    }
+    memcpy(dest, src, sizeof(*dest));
+
+#ifndef OPENSSL_NO_KRB5
+    dest->krb5_client_princ_len = dest->krb5_client_princ_len;
+    if (src->krb5_client_princ_len > 0)
+        memcpy(dest->krb5_client_princ, src->krb5_client_princ,
+               src->krb5_client_princ_len);
+#endif
+
+#ifndef OPENSSL_NO_PSK
+    if (src->psk_identity_hint) {
+        dest->psk_identity_hint = BUF_strdup(src->psk_identity_hint);
+        if (dest->psk_identity_hint == NULL) {
+            goto err;
+        }
+    } else {
+        dest->psk_identity_hint = NULL;
+    }
+    if (src->psk_identity) {
+        dest->psk_identity = BUF_strdup(src->psk_identity);
+        if (dest->psk_identity == NULL) {
+            goto err;
+        }
+    } else {
+        dest->psk_identity = NULL;
+    }
+#endif
+
+    if (src->sess_cert != NULL)
+        CRYPTO_add(&src->sess_cert->references, 1, CRYPTO_LOCK_SSL_SESS_CERT);
+
+    if (src->peer != NULL)
+        CRYPTO_add(&src->peer->references, 1, CRYPTO_LOCK_X509);
+
+    dest->references = 1;
+
+    if(src->ciphers != NULL) {
+        dest->ciphers = sk_SSL_CIPHER_dup(src->ciphers);
+        if (dest->ciphers == NULL)
+            goto err;
+    } else {
+        dest->ciphers = NULL;
+    }
+
+    if (!CRYPTO_dup_ex_data(CRYPTO_EX_INDEX_SSL_SESSION,
+                                            &dest->ex_data, &src->ex_data)) {
+        goto err;
+    }
+
+    /* We deliberately don't copy the prev and next pointers */
+    dest->prev = NULL;
+    dest->next = NULL;
+
+#ifndef OPENSSL_NO_TLSEXT
+    if (src->tlsext_hostname) {
+        dest->tlsext_hostname = BUF_strdup(src->tlsext_hostname);
+        if (dest->tlsext_hostname == NULL) {
+            goto err;
+        }
+    } else {
+        dest->tlsext_hostname = NULL;
+    }
+# ifndef OPENSSL_NO_EC
+    if (src->tlsext_ecpointformatlist) {
+        dest->tlsext_ecpointformatlist =
+            BUF_memdup(src->tlsext_ecpointformatlist,
+                       src->tlsext_ecpointformatlist_length);
+        if (dest->tlsext_ecpointformatlist == NULL)
+            goto err;
+        dest->tlsext_ecpointformatlist_length =
+            src->tlsext_ecpointformatlist_length;
+    }
+    if (src->tlsext_ellipticcurvelist) {
+        dest->tlsext_ellipticcurvelist =
+            BUF_memdup(src->tlsext_ellipticcurvelist,
+                       src->tlsext_ellipticcurvelist_length);
+        if (dest->tlsext_ellipticcurvelist == NULL)
+            goto err;
+        dest->tlsext_ellipticcurvelist_length =
+            src->tlsext_ellipticcurvelist_length;
+    }
+# endif
+#endif
+
+    if (ticket != 0) {
+        dest->tlsext_tick_lifetime_hint = src->tlsext_tick_lifetime_hint;
+        dest->tlsext_ticklen = src->tlsext_ticklen;
+        if((dest->tlsext_tick = OPENSSL_malloc(src->tlsext_ticklen)) == NULL) {
+            goto err;
+        }
+    }
+
+#ifndef OPENSSL_NO_SRP
+    dest->srp_username = NULL;
+    if (src->srp_username) {
+        dest->srp_username = BUF_strdup(src->srp_username);
+        if (dest->srp_username == NULL) {
+            goto err;
+        }
+    } else {
+        dest->srp_username = NULL;
+    }
+#endif
+
+    return dest;
+err:
+    SSLerr(SSL_F_SSL_SESSION_DUP, ERR_R_MALLOC_FAILURE);
+    SSL_SESSION_free(dest);
+    return NULL;
+}
+
 const unsigned char *SSL_SESSION_get_id(const SSL_SESSION *s,
                                         unsigned int *len)
 {