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Re: [net/bpf] 3051bf36c2 BUG: unable to handle kernel paging request at 0000a7cf

From Kees Cook <keescook@chromium.org>
Newsgroups linux.kernel
Subject Re: [net/bpf] 3051bf36c2 BUG: unable to handle kernel paging request at 0000a7cf
Date 2017-03-09 06:40 +0100
Message-ID <tiYXT-xV-1@gated-at.bofh.it> (permalink)
References (2 earlier) <tgGC5-885-3@gated-at.bofh.it> <tiPrA-2uR-1@gated-at.bofh.it> <tiSfL-4qJ-7@gated-at.bofh.it> <tiSps-4tU-13@gated-at.bofh.it> <tiU7T-5GA-5@gated-at.bofh.it>
Organization linux.* mail to news gateway

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On Wed, Mar 8, 2017 at 3:55 PM, Laura Abbott <labbott@redhat.com> wrote:
> On 03/08/2017 02:36 PM, Kees Cook wrote:
>> On Wed, Mar 8, 2017 at 2:27 PM, Daniel Borkmann <daniel@iogearbox.net> wrote:
>>> [   28.474232] rodata_test: test data was not read only
>>> [...]
>>
>> In my tests so far, I've never been able to get rodata_test to fail
>> (Qemu 2.5.0, Ubuntu). I'll retry with your .config and see if I can
>> recheck under Qemu 2.7.1. Do you see these failures on real hardware?
>>
>> -Kees
>>
>
> FWIW, I'm seeing the same issue with qemu 2.6.2 and 2.8.0 on Fedora 24
> and rawhide respectively.
>
> I also notice that CONFIG_X86_PAE is turned off in the defconfig. If
> I set CONFIG_HIGHMEM_64G which turns on CONFIG_X86_PAE the problem
> goes away. I can't tell if this is an indication of magically hiding
> the TLB problem or if there is an issue with !X86_PAE invalidation.

I found my difference. I normally run qemu with "-cpu host" which
makes the failure go away. With "-cpu kvm64", I see the rodata_test
failure immediately. Seems like this may be a kvm cpu feature
emulation bug? I'll see if I can find the specific cpu feature in the
morning...

-Kees

-- 
Kees Cook
Pixel Security

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Thread

Re: [net/bpf] 3051bf36c2 BUG: unable to handle kernel paging request  at 0000a7cf Fengguang Wu <fengguang.wu@intel.com> - 2017-03-02 21:30 +0100
  Re: [net/bpf] 3051bf36c2 BUG: unable to handle kernel paging request  at 0000a7cf Daniel Borkmann <daniel@iogearbox.net> - 2017-03-02 22:40 +0100
    Re: [net/bpf] 3051bf36c2 BUG: unable to handle kernel paging request  at 0000a7cf Linus Torvalds <torvalds@linux-foundation.org> - 2017-03-08 20:30 +0100
      Re: [net/bpf] 3051bf36c2 BUG: unable to handle kernel paging request  at 0000a7cf Kees Cook <keescook@chromium.org> - 2017-03-08 23:40 +0100
        Re: [net/bpf] 3051bf36c2 BUG: unable to handle kernel paging request  at 0000a7cf Daniel Borkmann <daniel@iogearbox.net> - 2017-03-09 00:20 +0100
        Re: [net/bpf] 3051bf36c2 BUG: unable to handle kernel paging request  at 0000a7cf Laura Abbott <labbott@redhat.com> - 2017-03-09 01:30 +0100
          Re: [net/bpf] 3051bf36c2 BUG: unable to handle kernel paging request  at 0000a7cf Kees Cook <keescook@chromium.org> - 2017-03-09 06:40 +0100
            Re: [net/bpf] 3051bf36c2 BUG: unable to handle kernel paging request  at 0000a7cf Daniel Borkmann <daniel@iogearbox.net> - 2017-03-09 14:10 +0100
              Re: [net/bpf] 3051bf36c2 BUG: unable to handle kernel paging request  at 0000a7cf Thomas Gleixner <tglx@linutronix.de> - 2017-03-09 14:20 +0100
                Re: [net/bpf] 3051bf36c2 BUG: unable to handle kernel paging request  at 0000a7cf Daniel Borkmann <daniel@iogearbox.net> - 2017-03-09 15:10 +0100
                Re: [net/bpf] 3051bf36c2 BUG: unable to handle kernel paging request  at 0000a7cf Thomas Gleixner <tglx@linutronix.de> - 2017-03-09 16:00 +0100
                Re: [net/bpf] 3051bf36c2 BUG: unable to handle kernel paging request  at 0000a7cf Daniel Borkmann <daniel@iogearbox.net> - 2017-03-09 19:00 +0100
                Re: [net/bpf] 3051bf36c2 BUG: unable to handle kernel paging  request at 0000a7cf David Miller <davem@davemloft.net> - 2017-03-09 19:10 +0100
                Re: [net/bpf] 3051bf36c2 BUG: unable to handle kernel paging request  at 0000a7cf Linus Torvalds <torvalds@linux-foundation.org> - 2017-03-09 19:20 +0100
                Re: [net/bpf] 3051bf36c2 BUG: unable to handle kernel paging request  at 0000a7cf Linus Torvalds <torvalds@linux-foundation.org> - 2017-03-09 19:20 +0100
                Re: [net/bpf] 3051bf36c2 BUG: unable to handle kernel paging request  at 0000a7cf Daniel Borkmann <daniel@iogearbox.net> - 2017-03-09 19:40 +0100
                Re: [net/bpf] 3051bf36c2 BUG: unable to handle kernel paging request  at 0000a7cf Daniel Borkmann <daniel@iogearbox.net> - 2017-03-09 22:40 +0100
                Re: [net/bpf] 3051bf36c2 BUG: unable to handle kernel paging request  at 0000a7cf Borislav Petkov <bp@suse.de> - 2017-03-09 23:10 +0100
                Re: [net/bpf] 3051bf36c2 BUG: unable to handle kernel paging request  at 0000a7cf Daniel Borkmann <daniel@iogearbox.net> - 2017-03-09 23:20 +0100
                Re: [net/bpf] 3051bf36c2 BUG: unable to handle kernel paging request  at 0000a7cf Borislav Petkov <bp@suse.de> - 2017-03-09 23:50 +0100
                Re: [net/bpf] 3051bf36c2 BUG: unable to handle kernel paging request  at 0000a7cf Linus Torvalds <torvalds@linux-foundation.org> - 2017-03-10 00:30 +0100
                Re: [net/bpf] 3051bf36c2 BUG: unable to handle kernel paging request  at 0000a7cf Borislav Petkov <bp@suse.de> - 2017-03-10 00:50 +0100
                Re: [net/bpf] 3051bf36c2 BUG: unable to handle kernel paging request  at 0000a7cf Daniel Borkmann <daniel@iogearbox.net> - 2017-03-10 01:20 +0100
                Re: [net/bpf] 3051bf36c2 BUG: unable to handle kernel paging request  at 0000a7cf Borislav Petkov <bp@suse.de> - 2017-03-12 22:50 +0100
                Re: [net/bpf] 3051bf36c2 BUG: unable to handle kernel paging request  at 0000a7cf Borislav Petkov <bp@suse.de> - 2017-03-09 23:20 +0100
                Re: [net/bpf] 3051bf36c2 BUG: unable to handle kernel paging request  at 0000a7cf Daniel Borkmann <daniel@iogearbox.net> - 2017-03-09 16:00 +0100
                Re: [net/bpf] 3051bf36c2 BUG: unable to handle kernel paging request  at 0000a7cf Linus Torvalds <torvalds@linux-foundation.org> - 2017-03-09 18:50 +0100
      Re: [net/bpf] 3051bf36c2 BUG: unable to handle kernel paging request  at 0000a7cf Linus Torvalds <torvalds@linux-foundation.org> - 2017-03-08 23:50 +0100
        Re: [net/bpf] 3051bf36c2 BUG: unable to handle kernel paging request  at 0000a7cf Fengguang Wu <fengguang.wu@intel.com> - 2017-03-09 02:40 +0100
      Re: [net/bpf] 3051bf36c2 BUG: unable to handle kernel paging request  at 0000a7cf Thomas Gleixner <tglx@linutronix.de> - 2017-03-09 14:50 +0100

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