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Re: [RFC][PATCH] x86: Verify access_ok() context

From Peter Zijlstra <peterz@infradead.org>
Newsgroups linux.kernel
Subject Re: [RFC][PATCH] x86: Verify access_ok() context
Date 2017-01-20 09:30 +0100
Message-ID <t1CK7-4SH-23@gated-at.bofh.it> (permalink)
References (4 earlier) <sKYQF-3mX-9@gated-at.bofh.it> <t0m4G-5H7-13@gated-at.bofh.it> <t0nk6-6qK-11@gated-at.bofh.it> <t16Kd-1su-7@gated-at.bofh.it> <t18M1-2Gh-1@gated-at.bofh.it>
Organization linux.* mail to news gateway

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On Wed, Jan 18, 2017 at 04:19:47PM -0800, Andy Lutomirski wrote:
> ISTM even with pagefault_disable() in play, using access_ok() from,
> say, interrupt context is dangerous unless you've first checked that
> you're in a task.  But I guess that in_task() would still return
> false, e.g. in perf.

The test was created exactly because perf was using access_ok()
_wrongly_. See commit: ae31fe51a3cc ("perf/x86: Restore TASK_SIZE check
on frame pointer").

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Thread

Re: [RFC][PATCH] x86: Verify access_ok() context David Smith <dsmith@redhat.com> - 2017-01-16 21:30 +0100
  Re: [RFC][PATCH] x86: Verify access_ok() context Thomas Gleixner <tglx@linutronix.de> - 2017-01-16 22:50 +0100
    Re: [RFC][PATCH] x86: Verify access_ok() context David Smith <dsmith@redhat.com> - 2017-01-18 23:20 +0100
      Re: [RFC][PATCH] x86: Verify access_ok() context Andy Lutomirski <luto@amacapital.net> - 2017-01-19 01:30 +0100
        Re: [RFC][PATCH] x86: Verify access_ok() context David Smith <dsmith@redhat.com> - 2017-01-19 16:40 +0100
        Re: [RFC][PATCH] x86: Verify access_ok() context Peter Zijlstra <peterz@infradead.org> - 2017-01-20 09:30 +0100
          Re: [RFC][PATCH] x86: Verify access_ok() context Thomas Gleixner <tglx@linutronix.de> - 2017-01-20 10:00 +0100
      Re: [RFC][PATCH] x86: Verify access_ok() context Thomas Gleixner <tglx@linutronix.de> - 2017-01-19 19:50 +0100
        Re: [RFC][PATCH] x86: Verify access_ok() context "Frank Ch. Eigler" <fche@redhat.com> - 2017-01-19 21:30 +0100
          Re: [RFC][PATCH] x86: Verify access_ok() context Thomas Gleixner <tglx@linutronix.de> - 2017-01-19 22:20 +0100
            Re: [RFC][PATCH] x86: Verify access_ok() context "Frank Ch. Eigler" <fche@redhat.com> - 2017-01-19 22:30 +0100
              Re: [RFC][PATCH] x86: Verify access_ok() context Peter Zijlstra <peterz@infradead.org> - 2017-01-19 23:30 +0100
              Re: [RFC][PATCH] x86: Verify access_ok() context Thomas Gleixner <tglx@linutronix.de> - 2017-01-20 00:50 +0100

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