Fix ex_data and session_dup issues

Code was added in commit b3c31a65 that overwrote the last ex_data value
using CRYPTO_dup_ex_data() causing a memory leak, and potentially
confusing the ex_data dup() callback.

In ssl_session_dup(), fix error handling (properly reference and up-ref
shared data) and new-up the ex_data before calling CRYPTO_dup_ex_data();
all other structures that dup ex_data have the destination ex_data new'd
before the dup.

Fix up some of the ex_data documentation.

Reviewed-by: Matt Caswell <matt@openssl.org>
Reviewed-by: Rich Salz <rsalz@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/3625)

4 files changed, 143 insertions, 18 deletions

diff --git a/crypto/ex_data.c b/crypto/ex_data.c
index 4a3201a953..22c4d3d9b9 100644
--- a/crypto/ex_data.c
+++ b/crypto/ex_data.c
@@ -287,7 +287,14 @@ int CRYPTO_dup_ex_data(int class_index, CRYPTO_EX_DATA *to,
         CRYPTOerr(CRYPTO_F_CRYPTO_DUP_EX_DATA, ERR_R_MALLOC_FAILURE);
         return 0;
     }
-    if (!CRYPTO_set_ex_data(to, mx - 1, NULL))
+    /*
+     * Make sure the ex_data stack is at least |mx| elements long to avoid
+     * issues in the for loop that follows; so go get the |mx|'th element
+     * (if it does not exist CRYPTO_get_ex_data() returns NULL), and assign
+     * to itself. This is normally a no-op; but ensures the stack is the
+     * proper size
+     */
+    if (!CRYPTO_set_ex_data(to, mx - 1, CRYPTO_get_ex_data(to, mx - 1)))
         goto err;
 
     for (i = 0; i < mx; i++) {
diff --git a/doc/crypto/CRYPTO_get_ex_new_index.pod b/doc/crypto/CRYPTO_get_ex_new_index.pod
index 0853ce588c..a5bf620972 100644
--- a/doc/crypto/CRYPTO_get_ex_new_index.pod
+++ b/doc/crypto/CRYPTO_get_ex_new_index.pod
@@ -17,8 +17,8 @@ CRYPTO_get_ex_data, CRYPTO_free_ex_data, CRYPTO_new_ex_data
                 CRYPTO_EX_dup *dup_func,
                 CRYPTO_EX_free *free_func);
 
- typedef int CRYPTO_EX_new(void *parent, void *ptr, CRYPTO_EX_DATA *ad,
-                           int idx, long argl, void *argp);
+ typedef void CRYPTO_EX_new(void *parent, void *ptr, CRYPTO_EX_DATA *ad,
+                            int idx, long argl, void *argp);
  typedef void CRYPTO_EX_free(void *parent, void *ptr, CRYPTO_EX_DATA *ad,
                              int idx, long argl, void *argp);
  typedef int CRYPTO_EX_dup(CRYPTO_EX_DATA *to, const CRYPTO_EX_DATA *from,
@@ -128,7 +128,8 @@ initially registered via CRYPTO_get_ex_new_index() and can be used if
 the same callback handles different types of exdata.
 
 dup_func() is called when a structure is being copied.  This is only done
-for B<SSL> and B<SSL_SESSION> objects.  The B<to> and B<from> parameters
+for B<SSL>, B<SSL_SESSION>, B<EC_KEY> objects and B<BIO> chains via
+BIO_dup_chain().  The B<to> and B<from> parameters
 are pointers to the destination and source B<CRYPTO_EX_DATA> structures,
 respectively.  The B<from_d> parameter needs to be cast to a B<void **pptr>
 as the API has currently the wrong signature; that will be changed in a
diff --git a/ssl/ssl_sess.c b/ssl/ssl_sess.c
index 3f068840b9..92ba599566 100644
--- a/ssl/ssl_sess.c
+++ b/ssl/ssl_sess.c
@@ -138,6 +138,8 @@ SSL_SESSION *ssl_session_dup(SSL_SESSION *src, int ticket)
 #ifndef OPENSSL_NO_SRP
     dest->srp_username = NULL;
 #endif
+    dest->peer_chain = NULL;
+    dest->peer = NULL;
     memset(&dest->ex_data, 0, sizeof(dest->ex_data));
 
     /* We deliberately don't copy the prev and next pointers */
@@ -150,8 +152,14 @@ SSL_SESSION *ssl_session_dup(SSL_SESSION *src, int ticket)
     if (dest->lock == NULL)
         goto err;
 
-    if (src->peer != NULL)
-        X509_up_ref(src->peer);
+    if (!CRYPTO_new_ex_data(CRYPTO_EX_INDEX_SSL_SESSION, dest, &dest->ex_data))
+        goto err;
+
+    if (src->peer != NULL) {
+        if (!X509_up_ref(src->peer))
+            goto err;
+        dest->peer = src->peer;
+    }
 
     if (src->peer_chain != NULL) {
         dest->peer_chain = X509_chain_up_ref(src->peer_chain);
@@ -207,7 +215,7 @@ SSL_SESSION *ssl_session_dup(SSL_SESSION *src, int ticket)
     }
 #endif
 
-    if (ticket != 0) {
+    if (ticket != 0 && src->tlsext_tick != NULL) {
         dest->tlsext_tick =
             OPENSSL_memdup(src->tlsext_tick, src->tlsext_ticklen);
         if (dest->tlsext_tick == NULL)
diff --git a/test/exdatatest.c b/test/exdatatest.c
index e0eadd32dd..7998622de8 100644
--- a/test/exdatatest.c
+++ b/test/exdatatest.c
@@ -15,6 +15,12 @@
 static long saved_argl;
 static void *saved_argp;
 static int saved_idx;
+static int saved_idx2;
+
+/*
+ * SIMPLE EX_DATA IMPLEMENTATION
+ * Apps explicitly set/get ex_data as needed
+ */
 
 static void exnew(void *parent, void *ptr, CRYPTO_EX_DATA *ad,
           int idx, long argl, void *argp)
@@ -43,6 +49,75 @@ static void exfree(void *parent, void *ptr, CRYPTO_EX_DATA *ad,
     OPENSSL_assert(argp == saved_argp);
 }
 
+/*
+ * PRE-ALLOCATED EX_DATA IMPLEMENTATION
+ * Extended data structure is allocated in exnew2/freed in exfree2
+ * Data is stored inside extended data structure
+ */
+
+typedef struct myobj_ex_data_st {
+    char *hello;
+    int new;
+    int dup;
+} MYOBJ_EX_DATA;
+
+static void exnew2(void *parent, void *ptr, CRYPTO_EX_DATA *ad,
+          int idx, long argl, void *argp)
+{
+    int ret;
+    MYOBJ_EX_DATA *ex_data;
+
+    OPENSSL_assert(idx == saved_idx2);
+    OPENSSL_assert(argl == saved_argl);
+    OPENSSL_assert(argp == saved_argp);
+    OPENSSL_assert(ptr == NULL);
+
+    ex_data = OPENSSL_zalloc(sizeof(*ex_data));
+    OPENSSL_assert(ex_data != NULL);
+    ret = CRYPTO_set_ex_data(ad, saved_idx2, ex_data);
+    OPENSSL_assert(ret);
+
+    ex_data->new = 1;
+}
+
+static int exdup2(CRYPTO_EX_DATA *to, const CRYPTO_EX_DATA *from,
+          void *from_d, int idx, long argl, void *argp)
+{
+    MYOBJ_EX_DATA **update_ex_data = (MYOBJ_EX_DATA**)from_d;
+    MYOBJ_EX_DATA *ex_data = CRYPTO_get_ex_data(to, saved_idx2);
+
+    OPENSSL_assert(idx == saved_idx2);
+    OPENSSL_assert(argl == saved_argl);
+    OPENSSL_assert(argp == saved_argp);
+    OPENSSL_assert(from_d != NULL);
+    OPENSSL_assert(*update_ex_data != NULL);
+    OPENSSL_assert(ex_data != NULL);
+    OPENSSL_assert(ex_data->new);
+
+    /* Copy hello over */
+    ex_data->hello = (*update_ex_data)->hello;
+    /* indicate this is a dup */
+    ex_data->dup = 1;
+    /* Keep my original ex_data */
+    *update_ex_data = ex_data;
+    return 1;
+}
+
+static void exfree2(void *parent, void *ptr, CRYPTO_EX_DATA *ad,
+            int idx, long argl, void *argp)
+{
+    MYOBJ_EX_DATA *ex_data = CRYPTO_get_ex_data(ad, saved_idx2);
+    int ret;
+
+    OPENSSL_assert(ex_data != NULL);
+    OPENSSL_free(ex_data);
+    OPENSSL_assert(idx == saved_idx2);
+    OPENSSL_assert(argl == saved_argl);
+    OPENSSL_assert(argp == saved_argp);
+    ret = CRYPTO_set_ex_data(ad, saved_idx2, NULL);
+    OPENSSL_assert(ret);
+}
+
 typedef struct myobj_st {
     CRYPTO_EX_DATA ex_data;
     int id;
@@ -71,6 +146,25 @@ static char *MYOBJ_gethello(MYOBJ *obj)
     return CRYPTO_get_ex_data(&obj->ex_data, saved_idx);
 }
 
+static void MYOBJ_sethello2(MYOBJ *obj, char *cp)
+{
+    MYOBJ_EX_DATA* ex_data = CRYPTO_get_ex_data(&obj->ex_data, saved_idx2);
+    if (ex_data != NULL)
+        ex_data->hello = cp;
+    else
+        obj->st = 0;
+}
+
+static char *MYOBJ_gethello2(MYOBJ *obj)
+{
+    MYOBJ_EX_DATA* ex_data = CRYPTO_get_ex_data(&obj->ex_data, saved_idx2);
+    if (ex_data != NULL)
+        return ex_data->hello;
+
+    obj->st = 0;
+    return NULL;
+}
+
 static void MYOBJ_free(MYOBJ *obj)
 {
     CRYPTO_free_ex_data(CRYPTO_EX_INDEX_APP, obj, &obj->ex_data);
@@ -90,36 +184,51 @@ static MYOBJ *MYOBJ_dup(MYOBJ *in)
 int main()
 {
     MYOBJ *t1, *t2, *t3;
+    MYOBJ_EX_DATA *ex_data;
     const char *cp;
     char *p;
 
-    p = strdup("hello world");
+    p = OPENSSL_strdup("hello world");
     saved_argl = 21;
-    saved_argp = malloc(1);
+    saved_argp = OPENSSL_malloc(1);
     saved_idx = CRYPTO_get_ex_new_index(CRYPTO_EX_INDEX_APP,
                                         saved_argl, saved_argp,
                                         exnew, exdup, exfree);
+    saved_idx2 = CRYPTO_get_ex_new_index(CRYPTO_EX_INDEX_APP,
+                                         saved_argl, saved_argp,
+                                         exnew2, exdup2, exfree2);
     t1 = MYOBJ_new();
     t2 = MYOBJ_new();
+    OPENSSL_assert(t1->st && t2->st);
+    ex_data = CRYPTO_get_ex_data(&t1->ex_data, saved_idx2);
+    OPENSSL_assert(ex_data != NULL);
+    ex_data = CRYPTO_get_ex_data(&t2->ex_data, saved_idx2);
+    OPENSSL_assert(ex_data != NULL);
     MYOBJ_sethello(t1, p);
     cp = MYOBJ_gethello(t1);
     OPENSSL_assert(cp == p);
-    if (cp != p)
-        return 1;
     cp = MYOBJ_gethello(t2);
     OPENSSL_assert(cp == NULL);
-    if (cp != NULL)
-        return 1;
+    MYOBJ_sethello2(t1, p);
+    cp = MYOBJ_gethello2(t1);
+    OPENSSL_assert(cp == p);
+    OPENSSL_assert(t1->st);
+    cp = MYOBJ_gethello2(t2);
+    OPENSSL_assert(cp == NULL);
+    OPENSSL_assert(t2->st);
     t3 = MYOBJ_dup(t1);
+    ex_data = CRYPTO_get_ex_data(&t3->ex_data, saved_idx2);
+    OPENSSL_assert(ex_data != NULL);
+    OPENSSL_assert(ex_data->dup);
     cp = MYOBJ_gethello(t3);
     OPENSSL_assert(cp == p);
-    if (cp != p)
-        return 1;
-    cp = MYOBJ_gethello(t2);
+    cp = MYOBJ_gethello2(t3);
+    OPENSSL_assert(cp == p);
+    OPENSSL_assert(t3->st);
     MYOBJ_free(t1);
     MYOBJ_free(t2);
     MYOBJ_free(t3);
-    free(saved_argp);
-    free(p);
+    OPENSSL_free(saved_argp);
+    OPENSSL_free(p);
     return 0;
 }