From: Joerg Roedel <joro@8bytes.org>
To: Borislav Petkov <bp@alien8.de>
Cc: Thomas Gleixner <tglx@linutronix.de>,
Paul Menzel <pmenzel@molgen.mpg.de>,
linux-mm@kvack.org, x86@kernel.org,
lkml <linux-kernel@vger.kernel.org>
Subject: Re: x86/mm: Found insecure W+X mapping at address (ptrval)/0xc00a0000
Date: Thu, 4 Oct 2018 10:03:21 +0200 [thread overview]
Message-ID: <20181004080321.GA3630@8bytes.org> (raw)
In-Reply-To: <20181003212255.GB28361@zn.tnic>
On Wed, Oct 03, 2018 at 11:22:55PM +0200, Borislav Petkov wrote:
> On Fri, Sep 28, 2018 at 04:55:19PM +0200, Thomas Gleixner wrote:
> > Sorry for the delay and thanks for the data. A quick diff did not reveal
> > anything obvious. I'll have a closer look and we probably need more (other)
> > information to nail that down.
I also triggered this when working in the PTI-x32 code. It always
happens on a 32-bit PAE kernel for me.
Tracking it down I ended up in (iirc) arch/x86/mm/pageattr.c
function static_protections():
/*
* The BIOS area between 640k and 1Mb needs to be executable for
* PCI BIOS based config access (CONFIG_PCI_GOBIOS) support.
*/
#ifdef CONFIG_PCI_BIOS
if (pcibios_enabled && within(pfn, BIOS_BEGIN >> PAGE_SHIFT, BIOS_END >> PAGE_SHIFT))
pgprot_val(forbidden) |= _PAGE_NX;
#endif
I think that is the reason we are seeing this in that configuration.
Regards,
Joerg
next prev parent reply other threads:[~2018-10-04 8:03 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-09-19 6:55 x86/mm: Found insecure W+X mapping at address (ptrval)/0xc00a0000 Paul Menzel
2018-09-19 8:09 ` Thomas Gleixner
2018-09-20 7:07 ` Paul Menzel
2018-09-20 22:51 ` Thomas Gleixner
2018-09-24 21:47 ` Paul Menzel
2018-09-28 14:55 ` Thomas Gleixner
2018-10-03 21:22 ` Borislav Petkov
2018-10-04 3:11 ` Paul Menzel
2018-10-04 7:48 ` Borislav Petkov
2018-10-04 8:03 ` Joerg Roedel [this message]
2018-10-04 8:14 ` Borislav Petkov
2018-10-04 8:40 ` Paul Menzel
2018-10-04 8:49 ` Borislav Petkov
2018-10-04 8:59 ` Paul Menzel
2018-10-04 10:54 ` Borislav Petkov
2018-10-04 11:00 ` Paul Menzel
2018-10-04 11:12 ` Borislav Petkov
2018-10-04 8:43 ` Joerg Roedel
2018-10-04 8:48 ` Borislav Petkov
2018-10-05 9:27 ` Thomas Gleixner
2018-10-05 9:39 ` Paul Menzel
2018-10-08 19:37 ` Thomas Gleixner
2018-10-08 20:08 ` Bjorn Helgaas
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