Follow @Openwall on Twitter for new release announcements and other news
[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Date: Tue, 20 Jun 2017 12:11:56 -0700
From: Kees Cook <>
To: Mark Rutland <>
Cc: Laura Abbott <>, Alexander Popov <>, 
	"" <>, PaX Team <>, 
	Brad Spengler <>, Tycho Andersen <>, 
	Ard Biesheuvel <>
Subject: Re: Re: [PATCH RFC v2 1/1] gcc-plugins: Add
 stackleak feature erasing the kernel stack at the end of syscalls

On Tue, Jun 20, 2017 at 4:20 AM, Mark Rutland <> wrote:
> On Tue, Jun 13, 2017 at 02:51:59PM -0700, Laura Abbott wrote:
>> On 06/09/2017 10:28 AM, Kees Cook wrote:
>> > It seems like it shouldn't be too hard to add on-user-return erasure
>> > code to other architectures too.
>> I played around getting this to compile for arm64 with a dummy
>> stack clearing function. arm64 is doing something special with the
>> efistub so it fails to link with
>> drivers/firmware/efi/libstub/arm-stub.c:45:(.init.text+0x54): relocation
>>       truncated to fit: R_AARCH64_CALL26 against undefined symbol `__efistub_track_stack'
>> The relocation to the .init.text section and appending __efistub happens after
>> compilation so the checks in the plugin itself don't work. I haven't come up
>> with a solution to not have the plugin run on the stub yet.
> Can we do something like what we do for KCOV, and (only) place the
> plugin-invoking flags to into CFLAGS_STACKLEAK, which we can filter out
> in scripts/Makefile.lib?

That seems fine to me, though plugins have tended to provide a
DISABLE_foo_bar_PLUGIN export (like used in ppc for turning off the
latent entropy plugin):

scripts/Makefile.gcc-plugins:    DISABLE_LATENT_ENTROPY_PLUGIN +=

arch/powerpc/kernel/Makefile:CFLAGS_cputable.o +=
arch/powerpc/kernel/Makefile:CFLAGS_prom_init.o +=


Kees Cook
Pixel Security

Powered by blists - more mailing lists

Confused about mailing lists and their use? Read about mailing lists on Wikipedia and check out these guidelines on proper formatting of your messages.