lists  /  announce  owl-users  owl-dev  john-users  john-dev  passwdqc-users  yescrypt  popa3d-users  /  oss-security  kernel-hardening  musl  sabotage  tlsify  passwords  /  crypt-dev  xvendor  /  Bugtraq  Full-Disclosure  linux-kernel  linux-netdev  linux-ext4  linux-hardening  PHC 
Open Source and information security mailing list archives
Hash Suite: Windows password security audit tool. GUI, reports in PDF.
[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Date:   Mon, 1 Nov 2021 00:36:18 +0100
From:   Ard Biesheuvel <>
To:     Peter Zijlstra <>
Cc:     Sami Tolvanen <>,
        Mark Rutland <>, X86 ML <>,
        Kees Cook <>,
        Josh Poimboeuf <>,
        Nathan Chancellor <>,
        Nick Desaulniers <>,
        Sedat Dilek <>,
        Steven Rostedt <>,,
        Linux Kernel Mailing List <>,
Subject: Re: [PATCH] static_call,x86: Robustify trampoline patching

On Sun, 31 Oct 2021 at 21:45, Peter Zijlstra <> wrote:
> On Sun, Oct 31, 2021 at 09:21:56PM +0100, Ard Biesheuvel wrote:
> > That means we can support static calls on arm64 now without breaking
> > Clang CFI, and work on a solution for the redundant jumps on a more
> > relaxed schedule.
> Yes, arm64 has a 'problem' with having already merged the clang-cfi
> stuff :/
> I'm hoping the x86 solution can be an alternative CFI scheme, I'm
> starting to really hate this one. And I'm not at all convinced the
> proposed scheme is the best possible scheme given the constraints of
> kernel code. AFAICT it's a compromise made in userspace.

Your scheme only works with IBT: the value of %r11 is under the
adversary's control so it could just point it at 'foo+0x10' if it
wants to call foo indirectly, and circumvent the check. So without IBT
(or BTI), I think the check fundamentally belongs in the caller, not
in the callee.

Powered by blists - more mailing lists