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[83.33.157.186]) by smtp.gmail.com with ESMTPSA id u14sm45638049wrr.1.2019.04.15.15.57.07 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 15 Apr 2019 15:57:07 -0700 (PDT) Subject: Re: [PATCH] x86/mm: Prevent bogus warnings with "noexec=off" To: Thomas Gleixner Cc: LKML , x86 team References: <92ac69b8-7e29-50e1-f460-4e7ac8c6b7ac@gmail.com> From: Xose Vazquez Perez Message-ID: <20066a63-4d7e-c0e9-23fa-4653d1dae8df@gmail.com> Date: Tue, 16 Apr 2019 00:57:06 +0200 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-GB Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 4/15/19 10:46 AM, Thomas Gleixner wrote: > Xose reported warnings when NX is disabled on the kernel command line. Thank you for doing the dirty work. > > __early_set_fixmap() triggers: > > attempted to set unsupported pgprot: 8000000000000163 > bits: 8000000000000000 > supported: 7fffffffffffffff > > WARNING: CPU: 0 PID: 0 at arch/x86/include/asm/pgtable.h:537 > __early_set_fixmap+0xa2/0xff > > because it uses __default_kernel_pte_mask to mask out unsupported bits. > > Use __supported_pte_mask instead. > > Disabling NX on the command line also triggers the NX warning in the page > table mapping check: > > WARNING: CPU: 1 PID: 1 at arch/x86/mm/dump_pagetables.c:262 note_page+0x2ae/0x650 > .... > > Make the warning depend on NX set in __supported_pte_mask. > > Reported-by: Xose Vazquez Perez And Tested-by: Xose Vazquez Perez > Signed-off-by: Thomas Gleixner > --- > arch/x86/mm/dump_pagetables.c | 3 ++- > arch/x86/mm/ioremap.c | 2 +- > 2 files changed, 3 insertions(+), 2 deletions(-) > > --- a/arch/x86/mm/dump_pagetables.c > +++ b/arch/x86/mm/dump_pagetables.c > @@ -259,7 +259,8 @@ static void note_wx(struct pg_state *st) > #endif > /* Account the WX pages */ > st->wx_pages += npages; > - WARN_ONCE(1, "x86/mm: Found insecure W+X mapping at address %pS\n", > + WARN_ONCE(__supported_pte_mask & _PAGE_NX, > + "x86/mm: Found insecure W+X mapping at address %pS\n", > (void *)st->start_address); > } > > --- a/arch/x86/mm/ioremap.c > +++ b/arch/x86/mm/ioremap.c > @@ -825,7 +825,7 @@ void __init __early_set_fixmap(enum fixe > pte = early_ioremap_pte(addr); > > /* Sanitize 'prot' against any unsupported bits: */ > - pgprot_val(flags) &= __default_kernel_pte_mask; > + pgprot_val(flags) &= __supported_pte_mask; > > if (pgprot_val(flags)) > set_pte(pte, pfn_pte(phys >> PAGE_SHIFT, flags)); >