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From: Nadav Amit <namit@vmware.com>
To: Andy Lutomirski <luto@kernel.org>
Cc: Ingo Molnar <mingo@redhat.com>,
	LKML <linux-kernel@vger.kernel.org>, X86 ML <x86@kernel.org>,
	"H. Peter Anvin" <hpa@zytor.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	Borislav Petkov <bp@alien8.de>,
	Dave Hansen <dave.hansen@linux.intel.com>,
	Peter Zijlstra <peterz@infradead.org>,
	"linux_dti@icloud.com" <linux_dti@icloud.com>,
	linux-integrity <linux-integrity@vger.kernel.org>,
	LSM List <linux-security-module@vger.kernel.org>,
	Rick Edgecombe <rick.p.edgecombe@intel.com>,
	Will Deacon <will.deacon@arm.com>
Subject: Re: [PATCH v7 13/14] module: Do not set nx for module memory before freeing
Date: Thu, 6 Dec 2018 18:56:14 +0000
Message-ID: <7B410C6F-A811-41DB-ADCE-4E4BF07CA96A@vmware.com> (raw)
In-Reply-To: <CALCETrWZf5sNmXU=yP1ZHxiBi=Z9d3G5FnWH08PasniG1hs26g@mail.gmail.com>

> On Dec 6, 2018, at 10:52 AM, Andy Lutomirski <luto@kernel.org> 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.

Sorry for my laziness. It just seems that every small thing I touch in
regard to W^X or text_poke() is broken, and I need to finish some other
“chores” first.


  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 [this message]
2018-12-06 20:21     ` Edgecombe, Rick P
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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