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Date: Thu, 07 Apr 2016 09:39:58 +0200 From: Daniel Borkmann <daniel@...earbox.net> To: Alexei Starovoitov <ast@...com> CC: "David S . Miller" <davem@...emloft.net>, netdev@...r.kernel.org Subject: Re: [PATCH net-next] bpf: simplify verifier register state assignments On 04/07/2016 04:39 AM, Alexei Starovoitov wrote: > verifier is using the following structure to track the state of registers: > struct reg_state { > enum bpf_reg_type type; > union { > int imm; > struct bpf_map *map_ptr; > }; > }; > and later on in states_equal() does memcmp(&old->regs[i], &cur->regs[i],..) > to find equivalent states. > Throughout the code of verifier there are assignements to 'imm' and 'map_ptr' > fields and it's not obvious that most of the assignments into 'imm' don't > need to clear extra 4 bytes (like mark_reg_unknown_value() does) to make sure > that memcmp doesn't go over junk left from 'map_ptr' assignment. > > Simplify the code by converting 'int' into 'long' > > Suggested-by: Daniel Borkmann <daniel@...earbox.net> > Signed-off-by: Alexei Starovoitov <ast@...nel.org> Acked-by: Daniel Borkmann <daniel@...earbox.net>
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