netdev - Re: [PATCH bpf-next] bpf: fix precision tracking

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Date:   Wed, 3 Jul 2019 11:50:24 +0200
From:   Daniel Borkmann <daniel@...earbox.net>
To:     Alexei Starovoitov <ast@...nel.org>, davem@...emloft.net
Cc:     netdev@...r.kernel.org, bpf@...r.kernel.org, kernel-team@...com
Subject: Re: [PATCH bpf-next] bpf: fix precision tracking

On 06/28/2019 06:24 PM, Alexei Starovoitov wrote:
> When equivalent state is found the current state needs to propagate precision marks.
> Otherwise the verifier will prune the search incorrectly.
> 
> There is a price for correctness:
>                       before      before    broken    fixed
>                       cnst spill  precise   precise
> bpf_lb-DLB_L3.o       1923        8128      1863      1898
> bpf_lb-DLB_L4.o       3077        6707      2468      2666
> bpf_lb-DUNKNOWN.o     1062        1062      544       544
> bpf_lxc-DDROP_ALL.o   166729      380712    22629     36823
> bpf_lxc-DUNKNOWN.o    174607      440652    28805     45325
> bpf_netdev.o          8407        31904     6801      7002
> bpf_overlay.o         5420        23569     4754      4858
> bpf_lxc_jit.o         39389       359445    50925     69631
> Overall precision tracking is still very effective.
> 
> Fixes: b5dc0163d8fd ("bpf: precise scalar_value tracking")
> Reported-by: Lawrence Brakmo <brakmo@...com>
> Signed-off-by: Alexei Starovoitov <ast@...nel.org>

Applied, thanks!