Subject: [PATCH 4/4] ef/libstub: arm/arm64: randomize the base of the UEFI rt services region

From: [email-masked] (James Morse)
Date: Fri, 07 Apr 2017 17:11:52 +0100

Hi Ard,

On 07/04/17 16:51, Ard Biesheuvel wrote:
> That is quite interesting, to be honest, because that patch should
> effectively be a NOP on systems that do not implement
> EFI_RNG_PROTOCOL.
> 
> Could you run this from the UEFI shell please?
> 
> http://people.linaro.org/~ard.biesheuvel/RngTest.efi

As you predicted:

Shell> RngTest.efi
UEFI RNG Protocol Testing :
----------------------------
 -- Locate UEFI RNG Protocol : [Fail - Status = Not Found]
Error reported: Not Found

> I would expect it to report that it has no EFI_RNG_PROTOCOL
> implementation. Could you also check whether the working kernel still
> works /after/ having executed that utility?

The broken kernel remains broken after running that test. reboot. The working
kernel continues to work after running that test.

(On Monday) I will try with just these efi changes on v4.11-rc. to try and
eliminate everything else in linux-next.

This is one of those firmware versions that prints lots of
> efi: [Firmware Bug]: IRQ flags corrupted (0x00000140=>0x00000100) by EFI
get_variable

Thanks,

James