Re: [PATCH 00/35] Shadow stacks for userspace

[Peter Zijlstra]

On Sat, Feb 05, 2022 at 12:21:12PM -0800, H.J. Lu wrote:

> setjmp/longjmp work on the same sigjmp_buf.  Shadow stack pointer
> is saved and restored, just like any other callee-saved registers.

How is having that shadow stack pointer in user-writable memory not a
problem? That seems like a prime target to subvert the whole shadow
stack machinery.