Fix the parameter types of the CRYPTO_EX_dup function type.

This fixes a strict aliasing issue in ui_dup_method_data.

The parameter type of CRYPTO_EX_dup's from_d parameter
is in fact void **, since it points to a pointer.

This function is rarely used, therefore fix the param type
although that may be considered an API breaking change.

Reviewed-by: Richard Levitte <levitte@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/2986)

crypto/ex_data.c

@@ -96,7 +96,7 @@ static void dummy_free(void *parent, void *ptr, CRYPTO_EX_DATA *ad, int idx,
 }
 
 static int dummy_dup(CRYPTO_EX_DATA *to, const CRYPTO_EX_DATA *from,
-                     void *from_d, int idx,
+                     void **from_d, int idx,
                      long argl, void *argp)
 {
     return 1;

crypto/ui/ui_util.c

@@ -71,9 +71,8 @@ static void ui_new_method_data(void *parent, void *ptr, CRYPTO_EX_DATA *ad,
 }
 
 static int ui_dup_method_data(CRYPTO_EX_DATA *to, const CRYPTO_EX_DATA *from,
-                              void *from_d, int idx, long argl, void *argp)
+                              void **pptr, int idx, long argl, void *argp)
 {
-    void **pptr = (void **)from_d;
     if (*pptr != NULL)
         *pptr = OPENSSL_memdup(*pptr, sizeof(struct pem_password_cb_data));
     return 1;

doc/man3/CRYPTO_get_ex_new_index.pod

@@ -23,7 +23,7 @@ CRYPTO_free_ex_data, CRYPTO_new_ex_data
  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,
-                           void *from_d, int idx, long argl, void *argp);
+                           void **from_d, int idx, long argl, void *argp);
 
  int CRYPTO_new_ex_data(int class_index, void *obj, CRYPTO_EX_DATA *ad)
 
@@ -140,10 +140,8 @@ dup_func() is called when a structure is being copied.  This is only done
 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
-future version.  The B<*pptr> is a pointer to the source exdata.
-When the dup_func() returns, the value in B<*pptr> is copied to the
+respectively.  The B<*from_d> parameter is a pointer to the source exdata.
+When the dup_func() returns, the value in B<*from_d> is copied to the
 destination ex_data.  If the pointer contained in B<*pptr> is not modified
 by the dup_func(), then both B<to> and B<from> will point to the same data.
 The B<idx>, B<argl> and B<argp> parameters are as described for the other
@@ -165,6 +163,8 @@ dup_func() should return 0 for failure and 1 for success.
 =head1 HISTORY
 
 CRYPTO_alloc_ex_data() was added in OpenSSL 3.0.
+The signature of the dup_func() callback was changed in OpenSSL 3.0 to use the
+type B<void **> for B<from_d>.  Previously this parameter was of type B<void *>.
 
 =head1 COPYRIGHT
 

include/openssl/crypto.h

@@ -201,7 +201,7 @@ typedef void CRYPTO_EX_new (void *parent, void *ptr, CRYPTO_EX_DATA *ad,
 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,
-                           void *from_d, int idx, long argl, void *argp);
+                           void **from_d, int idx, long argl, void *argp);
 __owur int CRYPTO_get_ex_new_index(int class_index, long argl, void *argp,
                                    CRYPTO_EX_new *new_func,
                                    CRYPTO_EX_dup *dup_func,

test/exdatatest.c

@@ -37,7 +37,7 @@ static void exnew(void *parent, void *ptr, CRYPTO_EX_DATA *ad,
 }
 
 static int exdup(CRYPTO_EX_DATA *to, const CRYPTO_EX_DATA *from,
-          void *from_d, int idx, long argl, void *argp)
+          void **from_d, int idx, long argl, void *argp)
 {
     if (!TEST_int_eq(idx, saved_idx)
         || !TEST_long_eq(argl, saved_argl)
@@ -87,7 +87,7 @@ static void exnew2(void *parent, void *ptr, CRYPTO_EX_DATA *ad,
 }
 
 static int exdup2(CRYPTO_EX_DATA *to, const CRYPTO_EX_DATA *from,
-          void *from_d, int idx, long argl, void *argp)
+          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 = NULL;