linux-kernel - Re: [PATCH 1/4] mm: add DEBUG

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Date:   Mon, 27 Apr 2020 12:42:41 -0700
From:   Andrew Morton <akpm@...ux-foundation.org>
To:     Zong Li <zong.li@...ive.com>
Cc:     Will Deacon <will@...nel.org>, linux-mm@...ck.org,
        "linux-kernel@...r.kernel.org List" <linux-kernel@...r.kernel.org>,
        Paul Walmsley <paul.walmsley@...ive.com>,
        Palmer Dabbelt <palmer@...belt.com>,
        linux-riscv <linux-riscv@...ts.infradead.org>,
        tglx@...utronix.de, mingo@...hat.com, bp@...en8.de, x86@...nel.org,
        hpa@...or.com, catalin.marinas@....com,
        linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH 1/4] mm: add DEBUG_WX support

On Mon, 27 Apr 2020 16:47:47 +0800 Zong Li <zong.li@...ive.com> wrote:

> > > +       This is useful for discovering cases where the kernel is leaving
> > > +       W+X mappings after applying NX, as such mappings are a security risk.
> > > +       This check also includes UXN, which should be set on all kernel
> > > +       mappings.
> >
> > "UXN" is the name of a bit in the arm64 page-table descriptors, so this
> > should be reworded now that it's in generic help text.
> >
> 
> It's exactly. Sorry for missing the statement.
> 
> Hi Andrew,
> Shall I send a next version patch to fix it? It should be "This is
> useful for discovering cases where the kernel is leaving W+X mappings
> after applying NX, as such mappings are a security risk." here.

I'll add this:

--- a/mm/Kconfig.debug~mm-add-debug_wx-support-fix
+++ a/mm/Kconfig.debug
@@ -128,8 +128,8 @@ config DEBUG_WX
 	help
 	  Generate a warning if any W+X mappings are found at boot.
 
-	  This is useful for discovering cases where the kernel is leaving
-	  W+X mappings after applying NX, as such mappings are a security risk.
+	  This is useful for discovering cases where the kernel is leaving W+X
+	  mappings after applying NX, as such mappings are a security risk.
 	  This check also includes UXN, which should be set on all kernel
 	  mappings.
 
_