linux-kernel - Re: [OOPS s390] Unable to handle kernel pointer dereference at virtual kernel address (null)

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Wed, 20 Apr 2011 22:34:54 -0400 (EDT)
From:	Stephen Powell <zlinuxman@...way.com>
To:	Heiko Carstens <heiko.carstens@...ibm.com>
Cc:	Jan Glauber <jang@...ux.vnet.ibm.com>,
	Jonathan Nieder <jrnieder@...il.com>,
	linux-s390@...r.kernel.org, linux-kernel@...r.kernel.org,
	622570@...s.debian.org
Subject: Re: [OOPS s390] Unable to handle kernel pointer dereference at
 virtual kernel address (null)

On Mon, 18 Apr 2011 07:51:41 -0400 (EDT), Heiko Carstens wrote:
> 
> That's a bug in the pfault interrupt code. After a cleanup patch which
> simplified lowcore accesses we are left with a dereference which shouldn't
> be there.  The patch below should fix it.
> The bug was introduced with 2.6.37-rc1.
> 
> diff --git a/arch/s390/mm/fault.c b/arch/s390/mm/fault.c
> index 9217e33..4cf85fe 100644
> --- a/arch/s390/mm/fault.c
> +++ b/arch/s390/mm/fault.c
> @@ -558,9 +558,9 @@ static void pfault_interrupt(unsigned int ext_int_code,
>  	 * Get the token (= address of the task structure of the affected task).
>  	 */
>  #ifdef CONFIG_64BIT
> -	tsk = *(struct task_struct **) param64;
> +	tsk = (struct task_struct *) param64;
>  #else
> -	tsk = *(struct task_struct **) param32;
> +	tsk = (struct task_struct *) param32;
>  #endif
>  
>  	if (subcode & 0x0080) {

I applied the above patch and re-built the kernel.  I did not apply
Jan Glauber's suggested patch, since Heiko's suggested patch seemed to be a
"direct hit".  I have had the server up for more than 24 hours now,
which is definitely a good sign.  Without this patch, I've not been able
to keep a 2.6.38 s390x kernel up for more than a few hours.  Unfortunately,
since I can't reproduce the problem on demand, I cannot say with 100%
certainty that the problem is fixed, but it looks good and makes sense.

-- 
  .''`.     Stephen Powell    
 : :'  :
 `. `'`
   `-
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/