Commit a3830831 authored by Richard Levitte's avatar Richard Levitte
Browse files

Replumbing: better reference counter control in ossl_method_construct() 



Fully assume that the method constructors use reference counting.
Otherwise, we may leak memory, or loose track and do a double free.

Reviewed-by: default avatarMatt Caswell <matt@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/8341)
parent 7bb19a0f

crypto/core_fetch.c

+20 −12
Original line number Diff line number Diff line
@@ -39,25 +39,33 @@ static int ossl_method_construct_this(OSSL_PROVIDER *provider, void *cbdata) 
                                            data->mcm_data)) == NULL)

            continue;



        /*

         * Note regarding putting the method in stores:

         *

         * we don't need to care if it actually got in or not here.

         * If it didn't get in, it will simply not be available when

         * ossl_method_construct() tries to get it from the store.

         *

         * It is *expected* that the put function increments the refcnt

         * of the passed method.

         */



        if (data->force_store || !no_store) {

            /*

             * If we haven't been told not to store,

             * add to the global store

             */

            if (!data->mcm->put(data->libctx, NULL,

            data->mcm->put(data->libctx, NULL,

                           thismap->property_definition,

                                method, data->mcm_data)) {

                data->mcm->destruct(method, data->mcm_data);

                continue;

            }

                           method, data->mcm_data);

        }



        if (!data->mcm->put(data->libctx, data->store,

        data->mcm->put(data->libctx, data->store,

                       thismap->property_definition,

                            method, data->mcm_data)) {

                       method, data->mcm_data);



        /* refcnt-- because we're dropping the reference */

        data->mcm->destruct(method, data->mcm_data);

            continue;

        }

    }



    return 1;

doc/internal/man3/ossl_method_construct.pod

+13 −1
Original line number Diff line number Diff line
@@ -49,6 +49,11 @@ functions given by the sub-system specific method creator through 
C<mcm> and the data in C<mcm_data> (which is passed by

ossl_method_construct()).



This function assumes that the sub-system method creator implements

reference counting and acts accordingly (i.e. it will call the

sub-system destruct() method to decrement the reference count when

appropriate).



=head2 Structures



A central part of constructing a sub-system specific method is to give
@@ -82,6 +87,8 @@ The method to be looked up should be identified with data from C<data> 
(which is the C<mcm_data> that was passed to ossl_construct_method())

and the provided property query C<propquery>.



This function is expected to increment the method's reference count.



=item put()



Places the C<method> created by the construct() function (see below)
@@ -96,6 +103,8 @@ The method should be associated with the given property definition 
C<propdef> and any identification data given through C<data> (which is

the C<mcm_data> that was passed to ossl_construct_method()).



This function is expected to increment the C<method>'s reference count.



=item construct()



Constructs a sub-system method given a dispatch table C<fns>.
@@ -106,9 +115,12 @@ is recommended. 
If such a reference is kept, the I<provider object> reference counter

must be incremented, using ossl_provider_upref().



This function is expected to set the method's reference count to 1.



=item desctruct()



Destruct the given C<method>.

Decrement the C<method>'s reference count, and destruct it when

the reference count reaches zero.



=back