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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 2015-08-22 11:10 +0200
Message-ID <q0cYi-64e-9@gated-at.bofh.it> (permalink)
References (4 earlier) <pYjhw-3w8-7@gated-at.bofh.it> <pYk3U-4GK-3@gated-at.bofh.it> <pZCL8-4sw-19@gated-at.bofh.it> <pZMhs-1oB-1@gated-at.bofh.it> <q01Jx-6TC-25@gated-at.bofh.it>
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On Fri, Aug 21, 2015 at 02:06:16PM -0700, H. Peter Anvin wrote:
> What I'm saying is that we do do STAC, which *disables* SMAP.  We have
> to do that because one pointer is known to be a user space pointer.
> 
> However, we currently don't verify that the *other* pointer is kernel
> space, which it is supposed to be (if not, we should be using
> copy_in_user).  We have to do this manually since we have to STAC which
> means SMAP doesn't do anything at all.  I believe it would be a good
> idea to add such checks (and they would even benefit non-SMAP hardware.)

Ah, ok, so we're on the same page.

And yep, Linus gave the probe_kernel_read() suggestion in another mail.

-- 
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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