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Message-Id: <20170516.150842.1909732065431538554.davem@davemloft.net> Date: Tue, 16 May 2017 15:08:42 -0400 (EDT) From: David Miller <davem@...emloft.net> To: daniel@...earbox.net Cc: ast@...com, alexei.starovoitov@...il.com, netdev@...r.kernel.org Subject: Re: [PATCH 2/3] bpf: Track alignment of MAP pointers in verifier. From: Daniel Borkmann <daniel@...earbox.net> Date: Mon, 15 May 2017 23:55:47 +0200 > I'm actually wondering about the min_align/aux_off/aux_off_align and > given this is not really related to varlen_map_access and we currently > just skip this. > > We should make sure that when env->strict_alignment is false that we > ignore any difference in min_align/aux_off/aux_off_align, afaik, the > min_align would also be set on regs other than ptr_to_pkt. Ok I see what you are saying, alignment related register state has to be taken into consideration during pruning but only when env->strict_alignment is true. ->min_align is set on any register upon which a calculation is performed. > What about compare_ptrs_to_packet() for when env->strict_alignment is > true in ptr_to_pkt case? Yes we need to do something there, and yes we do need testcases. You also remind me that I was thinking about whether we should propagate alignment state through branches. For example on the taken path of a JEQ we can set both arms of the test to have the largest of the two arms alignment.
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