Re: kernel tainted while exporting shash context using af_alg interface

[Stephan Mueller <smueller@chronox.de>]

Am Sonntag, 25. Oktober 2015, 11:56:27 schrieb Harsh Jain:

Hi Harsh,

>Hi,
>
>
>When trying to calculate HMAC(SHA1) with openssl using af-alg engine
>kernel crashes.Find below the command used and kernel. I have added
>some debug print in logs.
>
>Command used : ./openssl dgst -engine af_alg -sha1 -hmac "key" r.txt
>kernel version : 3.17.8
>
>Initial Investigation : In shash_desc structure tfm pointer contains
>5a5a5a5a5a5a5a5a(invalid pointer), when it triess to reference export
>function pointer it crashes. As per my understanding tfm object should
>have pointer of memory bloack allocated in
>"crypto_init_shash_ops_async" function
>
>Please give some pointers to debug the issue.Any documentation to
>understand the crypto-api code.

May I ask you to send 2 things: the source code of the OpenSSL af_alg engine 
that you use (IIRC it is not included upstream, I want to be sure I used the 
right one).

Further, can you attach an strace of the aforementioned command?

Note, I am playing and abusing the AF_ALG interface for quite some time with 
[1] but I did not come across any issues like the one you describe here.

[1] http://www.chronox.de/libkcapi.html

Ciao
Stephan