On Wed, 2024-10-23 at 09:17 -0700, Eduard Zingerman wrote: [...] > > We have other places where we assume that 64 bits is enough to specify > > stack slot index (linked regs, for instance). Do we need to update all > > of those now as well? If yes, maybe then it's better to make sure > > valid programs can never go beyond 512 bytes of stack even for > > bpf_fastcall?.. > > Specifically function frames. > This is a huge blunder from my side. The following places are problematic: - bpf_jmp_history_entry->flags - backtrack_state->stack_masks The following should be fine: - bpf_func_state->stack Not sure if anything else is affected (excluding scratched_stack_slots). I agree that we either need to update backtracking logic, or drop this stack extension logic.
