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From: Shakeel Butt <shakeelb@google.com>
To: Dave Hansen <dave.hansen@linux.intel.com>
Cc: LKML <linux-kernel@vger.kernel.org>,
	Linux MM <linux-mm@kvack.org>,
	stable@kernel.org, linuxram@us.ibm.com,
	Thomas Gleixner <tglx@linutronix.de>,
	Dave Hansen <dave.hansen@intel.com>,
	mpe@ellerman.id.au, Ingo Molnar <mingo@kernel.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	shuah@kernel.org
Subject: Re: [PATCH 4/9] x86, pkeys: override pkey when moving away from PROT_EXEC
Date: Wed, 25 Apr 2018 22:10:42 +0000	[thread overview]
Message-ID: <CALvZod5NTauM6MHW7D=h0mTDNYFd-1QyWrOxnhiixCgtHP=Taw@mail.gmail.com> (raw)
In-Reply-To: <20180326172727.025EBF16@viggo.jf.intel.com>

On Mon, Mar 26, 2018 at 5:27 PM, Dave Hansen
<dave.hansen@linux.intel.com> wrote:
>
> From: Dave Hansen <dave.hansen@linux.intel.com>
>
> I got a bug report that the following code (roughly) was
> causing a SIGSEGV:
>
>         mprotect(ptr, size, PROT_EXEC);
>         mprotect(ptr, size, PROT_NONE);
>         mprotect(ptr, size, PROT_READ);
>         *ptr = 100;
>
> The problem is hit when the mprotect(PROT_EXEC)
> is implicitly assigned a protection key to the VMA, and made
> that key ACCESS_DENY|WRITE_DENY.  The PROT_NONE mprotect()
> failed to remove the protection key, and the PROT_NONE->
> PROT_READ left the PTE usable, but the pkey still in place
> and left the memory inaccessible.
>
> To fix this, we ensure that we always "override" the pkee
> at mprotect() if the VMA does not have execute-only
> permissions, but the VMA has the execute-only pkey.
>
> We had a check for PROT_READ/WRITE, but it did not work
> for PROT_NONE.  This entirely removes the PROT_* checks,
> which ensures that PROT_NONE now works.
>
> Reported-by: Shakeel Butt <shakeelb@google.com>
>
> Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
> Fixes: 62b5f7d013f ("mm/core, x86/mm/pkeys: Add execute-only protection keys support")

Hi Dave, are you planning to send the next version of this patch or
going with this one?

  parent reply	other threads:[~2018-04-25 22:10 UTC|newest]

Thread overview: 31+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-03-26 17:27 [PATCH 0/9] [v2] x86, pkeys: two protection keys bug fixes Dave Hansen
2018-03-26 17:27 ` [PATCH 1/9] x86, pkeys: do not special case protection key 0 Dave Hansen
2018-03-26 17:47   ` Shuah Khan
2018-03-26 17:53     ` Dave Hansen
2018-03-26 17:58       ` Shuah Khan
2018-03-26 17:27 ` [PATCH 2/9] x86, pkeys, selftests: save off 'prot' for allocations Dave Hansen
2018-03-26 17:27 ` [PATCH 3/9] x86, pkeys, selftests: add a test for pkey 0 Dave Hansen
2018-03-26 17:27 ` [PATCH 4/9] x86, pkeys: override pkey when moving away from PROT_EXEC Dave Hansen
2018-04-07  0:09   ` Ram Pai
2018-04-07  0:47     ` Dave Hansen
2018-04-07  1:09       ` Ram Pai
2018-04-26 17:57         ` Dave Hansen
2018-04-30  7:51           ` Ram Pai
2018-04-30 16:36             ` Dave Hansen
2018-04-25 22:10   ` Shakeel Butt [this message]
2018-04-26  8:55     ` Thomas Gleixner
2018-04-26 18:17       ` Dave Hansen
2018-03-26 17:27 ` [PATCH 5/9] x86, pkeys, selftests: fix pointer math Dave Hansen
2018-03-26 17:27 ` [PATCH 6/9] x86, pkeys, selftests: fix pkey exhaustion test off-by-one Dave Hansen
2018-03-26 17:27 ` [PATCH 7/9] x86, pkeys, selftests: factor out "instruction page" Dave Hansen
2018-03-26 17:27 ` [PATCH 8/9] x86, pkeys, selftests: add allow faults on unknown keys Dave Hansen
2018-03-26 17:27 ` [PATCH 9/9] x86, pkeys, selftests: add PROT_EXEC test Dave Hansen
  -- strict thread matches above, loose matches on Subject: below --
2018-04-27 17:45 [PATCH 0/9] [v3] x86, pkeys: two protection keys bug fixes Dave Hansen
2018-04-27 17:45 ` [PATCH 4/9] x86, pkeys: override pkey when moving away from PROT_EXEC Dave Hansen
2018-03-23 18:09 [PATCH 0/9] x86, pkeys: two protection keys bug fixes Dave Hansen
2018-03-23 18:09 ` [PATCH 4/9] x86, pkeys: override pkey when moving away from PROT_EXEC Dave Hansen
2018-03-23 19:15   ` Shakeel Butt
2018-03-23 19:23     ` Dave Hansen
2018-03-23 19:27       ` Shakeel Butt
2018-03-23 19:29         ` Dave Hansen
2018-03-23 19:38       ` Thomas Gleixner
2018-03-23 19:45         ` Thomas Gleixner
2018-03-23 19:48           ` Dave Hansen

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