Follow @Openwall on Twitter for new release announcements and other news
[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Date: Wed, 25 Mar 2020 13:27:02 -0700
From: Kees Cook <>
To: "Reshetova, Elena" <>
Cc: Jann Horn <>, Thomas Gleixner <>,
	the arch/x86 maintainers <>,
	Andy Lutomirski <>,
	Peter Zijlstra <>,
	Catalin Marinas <>,
	Will Deacon <>, Mark Rutland <>,
	Alexander Potapenko <>,
	Ard Biesheuvel <>,
	Kernel Hardening <>,
	"" <>,
	Linux-MM <>,
	kernel list <>
Subject: Re: [PATCH v2 0/5] Optionally randomize kernel stack offset each

On Wed, Mar 25, 2020 at 12:15:12PM +0000, Reshetova, Elena wrote:
> > > Also, are you sure that it isn't possible to make the syscall that
> > > leaked its stack pointer never return to userspace (via ptrace or
> > > SIGSTOP or something like that), and therefore never realign its
> > > stack, while keeping some controlled data present on the syscall's
> > > stack?
> How would you reliably detect that a stack pointer has been leaked
> to userspace while it has been in a syscall? Does not seem to be a trivial
> task to me. 

Well, my expectation is that folks using this defense are also using
panic_on_warn sysctl, etc, so attackers don't get a chance to actually
_use_ register values spilled to dmesg.

Kees Cook

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.