[openssl-dev] [openssl.org #4518] OpenSSL-1.1.0-pre5 RSA_set0_key and related RSA_get0_*, RSA_set0_*, DSA_set0_* and DSA_get0_* problems

[Tomas Mraz]

On Út, 2016-04-26 at 18:25 +0000, Blumenthal, Uri - 0553 - MITLL wrote:
> On 4/26/16, 14:20 , "openssl-dev on behalf of Salz, Rich"
> <openssl-dev-bounces at openssl.org on behalf of rsalz at akamai.com>
> wrote:
> 
> > 
> > > 
> > > Look. If Doug noticed this, programmers less intimate with this
> > > API are
> > > much
> > > more likely to get stung by it. The protection against such a
> > > misunderstanding
> > > is cheap.
> > Is it?  
> I think it is. See Doug’s post.
> 
> 
> > 
> > And what is that protection?
> Checking whether (n, e) passed are pointing at rsa’s own, and not
> freeing
> them if they do. See Doug’s posting for the details.

No, that gives only false sense of correctness. And in another instance
you can try to get n, e from another RSA object and set it to a
different one and boom, you have doublefree or use-after-free in your
code.

I agree that this sequence - get + set should be more precisely
documented as forbidden but that's it.

-- 
Tomas Mraz
No matter how far down the wrong road you've gone, turn back.
                                              Turkish proverb
(You'll never know whether the road is wrong though.)