arm32 insecure W+X mapping

[Tim Harvey]

On Wed, Sep 15, 2021 at 2:45 AM Fabio Estevam <festevam at gmail.com> wrote:
>
> Hi Tim,
>
> [Adding the NXP folks]
>
> On Tue, Sep 7, 2021 at 2:49 PM Tim Harvey <tharvey at gateworks.com> wrote:
>
> > Shawn, Fabio and Pengutronix Kernel team,
> >
> > Do you know why we get 'Checked W+X mappings: FAILED, 1 W+X pages
> > found' messages for IMX6 with CONFIG_SUSPEND and CONFIG_DEBUG_WX
> > enabled due to to __arm_ioremap_exec call remapping ocram? [1]
>
> Not sure if this is related or not to the following behavior that I am seeing.
>
> On 5.15-rc1 I see the following on an imx6dl based board:
>
> [    0.123336] imx6q_suspend_init: failed to find ocram device!
>
> Also, suspend/resume is not working as expected:
>
> # echo enabled > /sys/class/tty/ttymxc0/power/wakeup
> # echo mem >  /sys/power/state
>
> (Sometimes it reboots the board, sometimes it does not enter in suspend).
>
> I haven't had a chance to debug this but just wanted to report it.
>

Fabio,

I don't see how this would be related. The warning and kernel dump are
a security warning that a page is left writable which could be used as
an attack vector. It doesn't constitute a bug necessarily but it is a
possible security hole that should be fixed. As Russell mentions there
would need to be some functions created to deal with it properly.

Best regards,

Tim