[openssl-users] Setting an OCSP stapling response on a DTLS server result in crash

[Matt Caswell]

On 29/08/16 17:37, Julien Vermillard wrote:
> I patched s_server to send a fake OCSP content (4 bytes).
> I suppose the server will just push that to the client and the client
> should fail complaining it's not a correct OCSP response.
> But the server crash with:
> ssl/statem/statem_dtls.c:127: OpenSSL internal error: assertion failed:
> s->init_num == (int)s->d1->w_msg_hdr.msg_len + DTLS1_HM_HEADER_LENGTH
> 
> Command line used:
> 
> ./openssl s_server -dtls1_2 -port 5684  -cipher
> ECDHE-ECDSA-AES256-CCM8:ECDHE-ECDSA-AES128-CCM8:PSK-AES256-CCM8:PSK-AES128-CCM8
> -CAfile ca.pem -cert server.pem -key server.key -chainCAfile bundle.pem
> -status -status_verbose -mtu 1200
> 
> and
> ./openssl s_client -dtls1_2 -port 5684 -psk 73656372657450534b -host
> localhost -cipher
> ECDHE-ECDSA-AES256-CCM8:ECDHE-ECDSA-AES128-CCM8:PSK-AES256-CCM8:PSK-AES128-CCM8
> -CAfile ca.pem -verify_hostname "IMEI:1234567890" -cert client.pem -key
> client.key -chainCAfile bundle-client.pem -status
> 
> 
> I attached also the test certificate and keys.

Actually, even the unpatched s_server has this problem. AFAICT this has
never worked for DTLS. I'm quite surprised no one has noticed before!
Even 1.0.2 has this problem (although the symptoms are different)...and
probably 1.0.1 although I haven't checked.

I have a fix here:

https://github.com/openssl/openssl/pull/1516

Only the first commit with the changes to ssl/statem/statem_srvr.c are
the fix itself. Everything else in the second commit is about adding a
test for this.

Matt

> 
> --
> Julien Vermillard
> 
> On Mon, Aug 29, 2016 at 6:17 PM, Julien Vermillard
> <jvermillard at gmail.com <mailto:jvermillard at gmail.com>> wrote:
> 
>     It's a mix of C and Go, so it's really not minimal, but I'll try to
>     modify s_server to see if I can reproduce it.
> 
>     --
>     Julien Vermillard
> 
>     On Mon, Aug 29, 2016 at 6:13 PM, Matt Caswell <matt at openssl.org
>     <mailto:matt at openssl.org>> wrote:
> 
> 
> 
>         On 29/08/16 17:08, Julien Vermillard wrote:
>         > I have a DTLS 1.2 server based on last master (commit
>         > d196305aa0de1fc38837c27cb1ea6e60af9dd98d)
>         > I try to add ocsp stapling support (based on code in s_server.c).
>         >
>         > Basicaly in my callback I set the OCSP response by:
>         >
>         >
>         >     if (SSL_set_tlsext_status_ocsp_resp(s,dataPtr,respLen) == 0) {
>         >         return SSL_TLSEXT_ERR_NOACK;
>         >     } else {
>         >         return SSL_TLSEXT_ERR_OK;
>         >     }
>         >
>         > but if my server manage to get an OCSP response it crash with this message:
>         >
>         > ssl/statem/statem_dtls.c:127: OpenSSL internal error: assertion failed:
>         > s->init_num == (int)s->d1->w_msg_hdr.msg_len + DTLS1_HM_HEADER_LENGTH
>         >
>         > Any clue?
> 
>         Do you have some minimal reproducer?
> 
>         Matt
> 
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> 
> 
> 
> 
>