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From: "Edgecombe, Rick P" <rick.p.edgecombe@intel.com>
To: "luto@kernel.org" <luto@kernel.org>,
	"jeyu@kernel.org" <jeyu@kernel.org>,
	"namit@vmware.com" <namit@vmware.com>
Cc: "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"peterz@infradead.org" <peterz@infradead.org>,
	"linux-integrity@vger.kernel.org"
	<linux-integrity@vger.kernel.org>,
	"tglx@linutronix.de" <tglx@linutronix.de>,
	"dave.hansen@linux.intel.com" <dave.hansen@linux.intel.com>,
	"nadav.amit@gmail.com" <nadav.amit@gmail.com>,
	"linux-security-module@vger.kernel.org" 
	<linux-security-module@vger.kernel.org>,
	"x86@kernel.org" <x86@kernel.org>,
	"hpa@zytor.com" <hpa@zytor.com>,
	"mingo@redhat.com" <mingo@redhat.com>,
	"linux_dti@icloud.com" <linux_dti@icloud.com>,
	"will.deacon@arm.com" <will.deacon@arm.com>,
	"bp@alien8.de" <bp@alien8.de>
Subject: Re: [PATCH v7 13/14] module: Do not set nx for module memory before freeing
Date: Thu, 6 Dec 2018 20:21:57 +0000
Message-ID: <55a4fb61164d7ecf5950e29d1fa2aea52a1b958f.camel@intel.com> (raw)
In-Reply-To: <CALCETrWZf5sNmXU=yP1ZHxiBi=Z9d3G5FnWH08PasniG1hs26g@mail.gmail.com>

On Thu, 2018-12-06 at 10:52 -0800, Andy Lutomirski wrote:
> On Wed, Dec 5, 2018 at 12:52 AM Nadav Amit <namit@vmware.com> wrote:
> > 
> > When module memory is about to be freed, there is no apparent reason to
> > make it (and its data) executable, but that's exactly what is done
> > today. This is not efficient and not secure.
> > 
> > There are various theories why it was done, but none of them seem as
> > something that really require it today. nios2 uses kmalloc for module
> > memory, but anyhow it does not change the PTEs of the module memory.  In
> > x86, changing vmalloc'd memory mappings also modifies the direct mapping
> > alias, but the NX-bit is not modified in such way.
> > 
> > So let's remove it. Andy suggested that the changes of the PTEs can be
> > avoided (excluding the direct-mapping alias), which is true. However,
> > in x86 it requires some cleanup of the contiguous page allocator, which
> > is outside of the scope of this patch-set.
> > 
> 
> 
> I'm okay with this, but I'd like to see Rick's stuff get rebased on
> top of it and clean it up for real.

Nadav,

Hmm, since you are trying to move things forward and not close all cases in one
swoop, would it make sense to split the modules W^X mission from this patchset?

Thanks,

Rick

  parent reply index

Thread overview: 30+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-12-05  1:33 [PATCH v7 00/14] x86/alternative: text_poke() enhancements Nadav Amit
2018-12-05  1:33 ` [PATCH v7 01/14] Fix "x86/alternatives: Lockdep-enforce text_mutex in text_poke*()" Nadav Amit
2018-12-05  1:33 ` [PATCH v7 02/14] x86/jump_label: Use text_poke_early() during early init Nadav Amit
2018-12-05  1:33 ` [PATCH v7 03/14] x86/mm: temporary mm struct Nadav Amit
2018-12-05  1:33 ` [PATCH v7 04/14] fork: provide a function for copying init_mm Nadav Amit
2018-12-05  1:33 ` [PATCH v7 05/14] x86/alternative: initializing temporary mm for patching Nadav Amit
2018-12-05  1:34 ` [PATCH v7 06/14] x86/alternative: use temporary mm for text poking Nadav Amit
2018-12-05  1:34 ` [PATCH v7 07/14] x86/kgdb: avoid redundant comparison of patched code Nadav Amit
2018-12-05  1:34 ` [PATCH v7 08/14] x86/ftrace: Use text_poke_*() infrastructure Nadav Amit
2018-12-06  0:06   ` Nadav Amit
2018-12-06 16:28     ` Ingo Molnar
2018-12-05  1:34 ` [PATCH v7 09/14] x86/kprobes: Instruction pages initialization enhancements Nadav Amit
2018-12-06 13:09   ` Masami Hiramatsu
2018-12-05  1:34 ` [PATCH v7 10/14] x86: avoid W^X being broken during modules loading Nadav Amit
2018-12-05  1:34 ` [PATCH v7 11/14] x86/jump-label: remove support for custom poker Nadav Amit
2018-12-05  1:34 ` [PATCH v7 12/14] x86/alternative: Remove the return value of text_poke_*() Nadav Amit
2018-12-05  1:34 ` [PATCH v7 13/14] module: Do not set nx for module memory before freeing Nadav Amit
2018-12-06  9:57   ` Peter Zijlstra
2018-12-06 17:28     ` Nadav Amit
2018-12-06 11:13   ` Andrea Parri
2018-12-06 18:52   ` Andy Lutomirski
2018-12-06 18:56     ` Nadav Amit
2018-12-06 20:21     ` Edgecombe, Rick P [this message]
2018-12-06 20:29       ` Nadav Amit
2018-12-13 14:10   ` Jessica Yu
2018-12-13 17:25     ` Nadav Amit
2018-12-05  1:34 ` [PATCH v7 14/14] module: Prevent module removal racing with text_poke() Nadav Amit
2018-12-06 10:01   ` Peter Zijlstra
2018-12-06 10:03 ` [PATCH v7 00/14] x86/alternative: text_poke() enhancements Peter Zijlstra
2018-12-10  1:06   ` Nadav Amit

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