On Thu, Oct 08, 2026 at 11:11:41PM +0000, Edgecombe, Rick P wrote: > On Thu, 2026-10-08 at 22:47 +0000, Richard Patel wrote: > > > But today setting EIP to an arbitrary point is fairly easy. But even in a > > > future > > > case of IBT enabled, shadow stack would still need enhancements for the > > > normal > > > 64 bit runtime to prevent this. > > > > What do you think of creating a shadow stack frame on signal delivery > > and popping that on sigreturn? I suppose that would need siglongjmp > > modifications and probably break CRIU. :( > > Yes I didn't know they did not parse the shadow stack signal frame > appropriately. That is unfortunate. But we can still evolve the shadow stack > ABI > by adding new modes to the enable prctl if we want.
In the case of CRIU, they are not only parsing, but crafting their own frames on the shadow stack. I suppose we can keep the kernel's parser lenient so it works with older CRIU frames even after IBT enablement.
