On Fri, 2026-10-09 at 11:36 +0000, Richard Patel wrote: > 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 >
Ah so the parsing is right, but they don't add the extra frames? > , 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. Yea we would need a backwards compatible frame. The real sigframes have the same problems to solve.
