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Re: [GIT PULL] x86/mm changes for v4.4

From Dave Jones <davej@codemonkey.org.uk>
Newsgroups linux.kernel
Subject Re: [GIT PULL] x86/mm changes for v4.4
Date 2015-11-05 00:40 +0100
Message-ID <qrfON-78K-13@gated-at.bofh.it> (permalink)
References <qqHN8-1ZB-23@gated-at.bofh.it> <qrbUR-4Bi-17@gated-at.bofh.it>
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On Wed, Nov 04, 2015 at 11:26:12AM -0800, Linus Torvalds wrote:
 > On Tue, Nov 3, 2015 at 3:16 AM, Ingo Molnar <mingo@kernel.org> wrote:
 > >
 > > The new CONFIG_DEBUG_WX=y warning is marked default-y if CONFIG_DEBUG_RODATA=y is
 > > already eanbled, as a special exception, as these bugs are hard to notice and this
 > > check already found several live bugs.
 > 
 > So this seems to be not very useful.
 > 
 >   ...
 >   Freeing unused kernel memory: 1068K (ffffffff8bcc0000 -
 > ffffffff8bdcb000)
 >   Write protecting the kernel read-only data: 12288k
 >   Freeing unused kernel memory: 1944K (ffff88000b61a000 - ffff88000b800000)
 >   Freeing unused kernel memory: 1372K (ffff88000baa9000 - ffff88000bc00000)
 >   ------------[ cut here ]------------
 >   WARNING: CPU: 7 PID: 1 at arch/x86/mm/dump_pagetables.c:225
 > note_page+0x5dc/0x780()
 >   x86/mm: Found insecure W+X mapping at address
 > ffff88000005f000/0xffff88000005f000
 >   ...
 >   x86/mm: Checked W+X mappings: FAILED, 165660 W+X pages found.
 >   ...
 > 
 > because it doesn't seem to give you any idea where to look for the
 > issue. Those 165660 pages come out to 647MB. Odd number.
 > 
 > Is this *supposed* to come out clean?

FWIW I'm seeing this too.

[    3.293503] x86/mm: Found insecure W+X mapping at address ffff880000800000/0xffff880000800000

Looking further up the dmesg I see that range is..

[    0.468368] ---[ Low Kernel Mapping ]---
[    0.468381] 0xffff880000000000-0xffff880000800000           8M     RW                 GLB NX pte
[    0.468391] 0xffff880000800000-0xffff880000900000           1M     RW                 GLB x  pte

Linus, does that match your trace too ? The 2nd low kernel mapping?

	Dave
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Thread

[GIT PULL] x86/mm changes for v4.4 Ingo Molnar <mingo@kernel.org> - 2015-11-03 12:20 +0100
  Re: [GIT PULL] x86/mm changes for v4.4 Linus Torvalds <torvalds@linux-foundation.org> - 2015-11-04 20:30 +0100
    Re: [GIT PULL] x86/mm changes for v4.4 Dave Jones <davej@codemonkey.org.uk> - 2015-11-05 00:40 +0100
      Re: [GIT PULL] x86/mm changes for v4.4 Linus Torvalds <torvalds@linux-foundation.org> - 2015-11-05 02:40 +0100
        Re: [GIT PULL] x86/mm changes for v4.4 Dave Jones <davej@codemonkey.org.uk> - 2015-11-05 03:20 +0100
          Re: [GIT PULL] x86/mm changes for v4.4 Linus Torvalds <torvalds@linux-foundation.org> - 2015-11-05 22:30 +0100
            Re: [GIT PULL] x86/mm changes for v4.4 Linus Torvalds <torvalds@linux-foundation.org> - 2015-11-05 22:40 +0100
              Re: [GIT PULL] x86/mm changes for v4.4 Matt Fleming <matt@codeblueprint.co.uk> - 2015-11-06 12:40 +0100
                Re: [GIT PULL] x86/mm changes for v4.4 Ingo Molnar <mingo@kernel.org> - 2015-11-07 08:10 +0100
                Re: [GIT PULL] x86/mm changes for v4.4 Matt Fleming <matt@codeblueprint.co.uk> - 2015-11-07 11:10 +0100
            Re: [GIT PULL] x86/mm changes for v4.4 Linus Torvalds <torvalds@linux-foundation.org> - 2015-11-05 23:10 +0100
              Re: [GIT PULL] x86/mm changes for v4.4 Borislav Petkov <bp@alien8.de> - 2015-11-05 23:30 +0100
            Re: [GIT PULL] x86/mm changes for v4.4 Ingo Molnar <mingo@kernel.org> - 2015-11-06 08:00 +0100
              Re: [GIT PULL] x86/mm changes for v4.4 Andy Lutomirski <luto@amacapital.net> - 2015-11-06 08:10 +0100
                Re: [GIT PULL] x86/mm changes for v4.4 Matt Fleming <matt@codeblueprint.co.uk> - 2015-11-06 14:10 +0100
                Re: [GIT PULL] x86/mm changes for v4.4 Borislav Petkov <bp@alien8.de> - 2015-11-06 14:30 +0100
                Re: [GIT PULL] x86/mm changes for v4.4 Ingo Molnar <mingo@kernel.org> - 2015-11-07 08:10 +0100
              Re: [GIT PULL] x86/mm changes for v4.4 Ingo Molnar <mingo@kernel.org> - 2015-11-06 08:50 +0100
              Re: [GIT PULL] x86/mm changes for v4.4 Matt Fleming <matt@codeblueprint.co.uk> - 2015-11-06 13:40 +0100
                Re: [GIT PULL] x86/mm changes for v4.4 Ingo Molnar <mingo@kernel.org> - 2015-11-07 08:10 +0100
                Re: [GIT PULL] x86/mm changes for v4.4 Ard Biesheuvel <ard.biesheuvel@linaro.org> - 2015-11-07 08:40 +0100
                Re: [GIT PULL] x86/mm changes for v4.4 Kees Cook <keescook@chromium.org> - 2015-11-08 08:00 +0100
                Re: [GIT PULL] x86/mm changes for v4.4 Ard Biesheuvel <ard.biesheuvel@linaro.org> - 2015-11-08 09:00 +0100
                Re: [GIT PULL] x86/mm changes for v4.4 Kees Cook <keescook@chromium.org> - 2015-11-09 22:10 +0100
                Re: [GIT PULL] x86/mm changes for v4.4 Ard Biesheuvel <ard.biesheuvel@linaro.org> - 2015-11-10 08:10 +0100
                Re: [GIT PULL] x86/mm changes for v4.4 Kees Cook <keescook@chromium.org> - 2015-11-10 21:20 +0100

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