linux-kernel - Re: amd_mce.c redundant if check?

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] [day] [month] [year] [list]

Message-ID: <20140820185755.GB18684@nazgul.tnic>
Date:	Wed, 20 Aug 2014 20:57:55 +0200
From:	Borislav Petkov <bp@...en8.de>
To:	Adam Duskett <aduskett@...il.com>
Cc:	linux-kernel@...r.kernel.org
Subject: Re: amd_mce.c redundant if check?

On Wed, Aug 20, 2014 at 11:18:21AM -0600, Adam Duskett wrote:
> I have recently come upon this section of code in
> arch/x86/kernel/cpu/mcheck/mce_amd.c that seems to be a redundant
> unnecessary if check.
> 
> 
> From line 170 - 176:
> 
> if (tr->set_lvt_off) {
> if (lvt_off_valid(tr->b, tr->lvt_off, lo, hi)) {
> /* set new lvt offset */
> hi &= ~MASK_LVTOFF_HI;
> hi |= tr->lvt_off << 20;
> }
> }
> 
> 
> This seems like it's not actually doing anything because it's setting
> the same value that the bit-field already has to itself.

Are you sure?

Just try to find out what MASK_LVTOFF_HI is and then do the operations
with a pen and paper to check whether something else actually happens.

-- 
Regards/Gruss,
    Boris.

Sent from a fat crate under my desk. Formatting is fine.
--
--
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/