linux-kernel - Re: [PATCH] x86: static_cpu_has_safe: discard dynamic check after init

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]

Message-ID: <56A16B6C.2070208@zytor.com>
Date:	Thu, 21 Jan 2016 15:36:12 -0800
From:	"H. Peter Anvin" <hpa@...or.com>
To:	Borislav Petkov <bp@...e.de>
Cc:	Andy Lutomirski <luto@...capital.net>,
	Brian Gerst <brgerst@...il.com>,
	the arch/x86 maintainers <x86@...nel.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Ingo Molnar <mingo@...nel.org>,
	Denys Vlasenko <dvlasenk@...hat.com>,
	Linus Torvalds <torvalds@...ux-foundation.org>
Subject: Re: [PATCH] x86: static_cpu_has_safe: discard dynamic check after
 init

On 01/21/16 14:56, Borislav Petkov wrote:
> 
> so this is silly: we're basically jumping after the JMP instruction
> itself. So that will be the case on !X86_BUG_SYSRET_SS_ATTRS CPUs.
> Still a two-byte and now even a useless JMP.
> 
> The right thing to do would be to generate a NOP simply.
> 

OK, so gcc isn't as clever as I thought.

	-hpa