On 12/15/2018 09:34 AM, Jiong Wang wrote: > Verifier is supposed to support sharing stack slot allocated to ptr with > SCALAR_VALUE for privileged program. However this doesn't happen for some > cases. > > The reason is verifier is not clearing slot_type STACK_SPILL for all bytes, > it only clears part of them, while verifier is using: > > slot_type[0] == STACK_SPILL > > as a convention to check one slot is ptr type. > > So, the consequence of partial clearing slot_type is verifier could treat a > partially overridden ptr slot, which should now be a SCALAR_VALUE slot, > still as ptr slot, and rejects some valid programs. > > Before this patch, test_xdp_noinline.o under bpf selftests, bpf_lxc.o and > bpf_netdev.o under Cilium bpf repo, when built with -mattr=+alu32 are > rejected due to this issue. After this patch, they all accepted. > > There is no processed insn number change before and after this patch on > Cilium bpf programs. > > Reviewed-by: Jakub Kicinski <jakub.kicin...@netronome.com> > Signed-off-by: Jiong Wang <jiong.w...@netronome.com>
Reviewed-by: Daniel Borkmann <dan...@iogearbox.net>
