On Tue, Sep 25, 2007, Bill Colvin wrote:
> I have been doing some EC test code with the Sept. 5 snapshot and have
> observed something that I find a little odd. So I thought I would
> mention it so someone could take a look to see if it is a bug or what is
> supposed to occur.
>
>
>
> I have a PEM file with an EC private key.
>
> I want to create an ephemeral private key for the same group.
>
> So my code fragments are as follows:
>
>
>
> EC_KEY *ecc_A=NULL;
>
> EC_KEY *ecc_E=NULL;
>
> const EC_GROUP *group=NULL;
>
>
>
> ecc_A = PEM_read_bio_ECPrivateKey( bio_in, NULL, NULL, NULL );
>
>
>
> group = EC_KEY_get0_group(ecc_A);
>
> ecc_E = EC_KEY_new();
>
> EC_KEY_set_group( ecc_E, group );
>
> EC_KEY_generate_key( ecc_E );
>
>
>
> Now the oddity occurs when I free the objects. If I have:
>
>
>
> if( ecc_E != NULL ) {EC_KEY_free( ecc_E ); printf("ecc_E
> freed\n");}
>
> if( ecc_A != NULL ) {EC_KEY_free( ecc_A ); printf("ecc_A
> freed\n");}
>
> if( group != NULL ) {EC_GROUP_free( (EC_GROUP*)group );
> printf("group freed\n");}
>
Some of the newer functions in OpenSSL follow a naming convention. If they
have a '0' such as *get0*() then the pointer retrieved is internal to the
parent structure and should *NOT* be freed up after use because it will be
freed when the parent structure is. If you free both up you get double frees
and undefined results.
If there is a '1' then a copy is retrieved and it *should* be freed up as well
as the parent structure.
Steve.
--
Dr Stephen N. Henson. Email, S/MIME and PGP keys: see homepage
OpenSSL project core developer and freelance consultant.
Funding needed! Details on homepage.
Homepage: http://www.drh-consultancy.demon.co.uk
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