From: Linus Torvalds <torvalds@linux-foundation.org>
To: Kees Cook <keescook@chromium.org>
Cc: Tommi Rantala <tommi.t.rantala@nokia.com>,
Dave Jones <davej@codemonkey.org.uk>,
Linux-MM <linux-mm@kvack.org>,
LKML <linux-kernel@vger.kernel.org>,
Laura Abbott <labbott@redhat.com>, Ingo Molnar <mingo@kernel.org>,
Josh Poimboeuf <jpoimboe@redhat.com>,
Mark Rutland <mark.rutland@arm.com>,
Eric Biggers <ebiggers@google.com>
Subject: Re: sudo x86info -a => kernel BUG at mm/usercopy.c:78!
Date: Tue, 4 Apr 2017 17:22:27 -0700 [thread overview]
Message-ID: <CA+55aFwv8QPBD4SMLw2Y7qkV4JceMc9NdOujbVM7PfcBpkhm3Q@mail.gmail.com> (raw)
In-Reply-To: <CA+55aFzSzemLt+GeynyavM7HzsOjGBrG=_S6XMFV=Xc1mn-UGA@mail.gmail.com>
On Tue, Apr 4, 2017 at 3:55 PM, Linus Torvalds
<torvalds@linux-foundation.org> wrote:
>
> I already explained what the likely fix is: make devmem_is_allowed()
> return a ternary value, so that those things that *do* read the BIOS
> area can just continue to do so, but they see zeroes for the parts
> that the kernel has taken over.
Actually, a simpler solution might be to
(a) keep the binary value
(b) remove the test for the low 1M
(c) to avoid breakage, don't return _error_, but just always read zero
that also removes (or at least makes it much more expensive) a signal
of which pages are kernel allocated vs BIOS allocated.
Linus
WARNING: multiple messages have this Message-ID (diff)
From: Linus Torvalds <torvalds@linux-foundation.org>
To: Kees Cook <keescook@chromium.org>
Cc: Tommi Rantala <tommi.t.rantala@nokia.com>,
Dave Jones <davej@codemonkey.org.uk>,
Linux-MM <linux-mm@kvack.org>,
LKML <linux-kernel@vger.kernel.org>,
Laura Abbott <labbott@redhat.com>, Ingo Molnar <mingo@kernel.org>,
Josh Poimboeuf <jpoimboe@redhat.com>,
Mark Rutland <mark.rutland@arm.com>,
Eric Biggers <ebiggers@google.com>
Subject: Re: sudo x86info -a => kernel BUG at mm/usercopy.c:78!
Date: Tue, 4 Apr 2017 17:22:27 -0700 [thread overview]
Message-ID: <CA+55aFwv8QPBD4SMLw2Y7qkV4JceMc9NdOujbVM7PfcBpkhm3Q@mail.gmail.com> (raw)
In-Reply-To: <CA+55aFzSzemLt+GeynyavM7HzsOjGBrG=_S6XMFV=Xc1mn-UGA@mail.gmail.com>
On Tue, Apr 4, 2017 at 3:55 PM, Linus Torvalds
<torvalds@linux-foundation.org> wrote:
>
> I already explained what the likely fix is: make devmem_is_allowed()
> return a ternary value, so that those things that *do* read the BIOS
> area can just continue to do so, but they see zeroes for the parts
> that the kernel has taken over.
Actually, a simpler solution might be to
(a) keep the binary value
(b) remove the test for the low 1M
(c) to avoid breakage, don't return _error_, but just always read zero
that also removes (or at least makes it much more expensive) a signal
of which pages are kernel allocated vs BIOS allocated.
Linus
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next prev parent reply other threads:[~2017-04-05 0:22 UTC|newest]
Thread overview: 48+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-03-30 6:44 sudo x86info -a => kernel BUG at mm/usercopy.c:78! Tommi Rantala
2017-03-30 6:44 ` Tommi Rantala
2017-03-30 16:45 ` Kees Cook
2017-03-30 16:45 ` Kees Cook
2017-03-30 17:20 ` Mark Rutland
2017-03-30 17:20 ` Mark Rutland
2017-03-30 17:27 ` Laura Abbott
2017-03-30 17:27 ` Laura Abbott
2017-03-30 17:37 ` Kees Cook
2017-03-30 17:37 ` Kees Cook
2017-03-30 17:44 ` Laura Abbott
2017-03-30 17:44 ` Laura Abbott
2017-03-31 5:44 ` Tommi Rantala
2017-03-31 5:44 ` Tommi Rantala
2017-03-30 19:41 ` Dave Jones
2017-03-30 19:41 ` Dave Jones
2017-03-30 19:52 ` Kees Cook
2017-03-30 19:52 ` Kees Cook
2017-03-30 20:01 ` Dave Jones
2017-03-30 20:01 ` Dave Jones
2017-03-31 5:40 ` Tommi Rantala
2017-03-31 5:40 ` Tommi Rantala
2017-03-31 6:59 ` Tommi Rantala
2017-03-31 6:59 ` Tommi Rantala
2017-03-31 17:17 ` Dave Jones
2017-03-31 17:17 ` Dave Jones
2017-03-31 17:32 ` Kees Cook
2017-03-31 17:32 ` Kees Cook
2017-03-31 18:03 ` Dave Jones
2017-03-31 18:03 ` Dave Jones
2017-03-31 18:57 ` Andy Lutomirski
2017-03-31 18:57 ` Andy Lutomirski
2017-03-31 18:26 ` Linus Torvalds
2017-03-31 18:26 ` Linus Torvalds
2017-03-31 19:32 ` Tommi Rantala
2017-03-31 19:32 ` Tommi Rantala
2017-04-04 22:37 ` Kees Cook
2017-04-04 22:37 ` Kees Cook
2017-04-04 22:55 ` Linus Torvalds
2017-04-04 22:55 ` Linus Torvalds
2017-04-04 22:59 ` Kees Cook
2017-04-04 22:59 ` Kees Cook
2017-04-05 0:22 ` Linus Torvalds [this message]
2017-04-05 0:22 ` Linus Torvalds
2017-04-05 19:39 ` Kees Cook
2017-04-05 19:39 ` Kees Cook
2017-03-31 23:58 ` Kees Cook
2017-03-31 23:58 ` Kees Cook
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