linux-kernel - Re: Is espfix64's double-fault thing OK on Xen?

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:	Mon, 14 Jul 2014 10:04:03 -0700
From:	"H. Peter Anvin" <hpa@...or.com>
To:	Andy Lutomirski <luto@...capital.net>,
	Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: Is espfix64's double-fault thing OK on Xen?

On 07/09/2014 04:17 PM, Andy Lutomirski wrote:
> This part in __do_double_fault looks fishy:
> 
>     cmpl $__KERNEL_CS,CS(%rdi)
>     jne do_double_fault
> 
> Shouldn't that be:
> 
>     test $3,CS(%rdi)
>     jnz do_double_fault
> 

No, it should be fine.  The *only* case where we need to do the espfix
magic is when we are on __KERNEL_CS.

	-hpa


--
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/