linux-kernel - Re: [PATCH 1/2] x86/mm/KASLR: Fix the wrong calculation of kalsr region initial size

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: <20180908133337.GT1740@192.168.1.3>
Date:   Sat, 8 Sep 2018 21:33:37 +0800
From:   Baoquan He <bhe@...hat.com>
To:     Thomas Gleixner <tglx@...utronix.de>
Cc:     mingo@...nel.org, hpa@...or.com, thgarnie@...gle.com,
        kirill.shutemov@...ux.intel.com, x86@...nel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/2] x86/mm/KASLR: Fix the wrong calculation of kalsr
 region initial size

On 09/08/18 at 02:10pm, Thomas Gleixner wrote:
> On Wed, 29 Aug 2018, Baoquan He wrote:
> 
> > In memory KASLR, __PHYSICAL_MASK_SHIFT is taken to calculate the
> > initial size of the direct mapping region. This is right in the
> > old code where __PHYSICAL_MASK_SHIFT was equal to MAX_PHYSMEM_BITS,
> > 46bit, and only 4-level mode was supported.
> > 
> > Later, in commit:
> > b83ce5ee91471d ("x86/mm/64: Make __PHYSICAL_MASK_SHIFT always 52"),
> > __PHYSICAL_MASK_SHIFT was changed to be 52 always, no matter it's
> > 5-level or 4-level. This is wrong for 4-level paging. Then when
> > adapt phyiscal memory region size based on available memory, it
> > will overflow if the amount of system RAM and the padding is bigger
> > than 64TB.
> > 
> > In fact, here MAX_PHYSMEM_BITS should be used instead. Fix it by
> > by replacing __PHYSICAL_MASK_SHIFT with MAX_PHYSMEM_BITS.
> > 
> > Signed-off-by: Baoquan He <bhe@...hat.com>
> 
> This lacks a fixes tag .....

Sure, I will add fix tag in this patch, and arrange a new patchset
according to discussion with Kirill after test.

Thanks
Baoquan