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Re: [x86] copy_from{to}_user question

From Borislav Petkov <bp@suse.de>
Newsgroups linux.kernel
Subject Re: [x86] copy_from{to}_user question
Date 2015-08-21 06:40 +0200
Message-ID <pZMhs-1oB-1@gated-at.bofh.it> (permalink)
References (2 earlier) <pWXCq-7m-3@gated-at.bofh.it> <pX3Rw-w6-7@gated-at.bofh.it> <pYjhw-3w8-7@gated-at.bofh.it> <pYk3U-4GK-3@gated-at.bofh.it> <pZCL8-4sw-19@gated-at.bofh.it>
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On Thu, Aug 20, 2015 at 11:22:43AM -0700, H. Peter Anvin wrote:
> There is a valid reason to do this, which is that currently
> copy_{to,from}_user() effectively bypass SMAP as they don't verify that
> the kernel pointer is actually a kernel pointer.

Well, we do STAC before we copy but SMAP is checking for supervisor
access to *user* data. But you say "kernel pointers" which is supervisor
data. What am I missing?

-- 
Regards/Gruss,
    Boris.

ECO tip #101: Trim your mails when you reply.

SUSE Linux GmbH, GF: Felix Imendörffer, Jane Smithard, Graham Norton, HRB 21284 (AG Nürnberg)
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Thread

Re: [x86] copy_from{to}_user question "H. Peter Anvin" <hpa@zytor.com> - 2015-08-20 20:30 +0200
  Re: [x86] copy_from{to}_user question Borislav Petkov <bp@suse.de> - 2015-08-21 06:40 +0200
    Re: [x86] copy_from{to}_user question "H. Peter Anvin" <hpa@zytor.com> - 2015-08-21 23:10 +0200
      Re: [x86] copy_from{to}_user question Borislav Petkov <bp@suse.de> - 2015-08-22 11:10 +0200
        Re: [x86] copy_from{to}_user question yalin wang <yalin.wang2010@gmail.com> - 2015-08-24 10:00 +0200
          Re: [x86] copy_from{to}_user question Jeff Epler <jepler@unpythonic.net> - 2015-08-24 14:10 +0200

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