netdev - Re: [PATCH bpf-next] bpf: fix too large copy from user in bpf_test

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Message-ID: <CAEf4BzZJ4dHHtWK-Kfiy2RRNsoK=3t8c94x_jxs6SDRVpcS-HA@mail.gmail.com>
Date:   Mon, 18 May 2020 17:15:39 -0700
From:   Andrii Nakryiko <andrii.nakryiko@...il.com>
To:     Jesper Dangaard Brouer <brouer@...hat.com>
Cc:     Networking <netdev@...r.kernel.org>, bpf <bpf@...r.kernel.org>,
        Daniel Borkmann <borkmann@...earbox.net>,
        Alexei Starovoitov <alexei.starovoitov@...il.com>,
        "David S. Miller" <davem@...emloft.net>
Subject: Re: [PATCH bpf-next] bpf: fix too large copy from user in bpf_test_init

On Mon, May 18, 2020 at 6:08 AM Jesper Dangaard Brouer
<brouer@...hat.com> wrote:
>
> Commit bc56c919fce7 ("bpf: Add xdp.frame_sz in bpf_prog_test_run_xdp().")
> recently changed bpf_prog_test_run_xdp() to use larger frames for XDP in
> order to test tail growing frames (via bpf_xdp_adjust_tail) and to have
> memory backing frame better resemble drivers.
>
> The commit contains a bug, as it tries to copy the max data size from
> userspace, instead of the size provided by userspace.  This cause XDP
> unit tests to fail sporadically with EFAULT, an unfortunate behavior.
> The fix is to only copy the size specified by userspace.
>
> Fixes: bc56c919fce7 ("bpf: Add xdp.frame_sz in bpf_prog_test_run_xdp().")
> Signed-off-by: Jesper Dangaard Brouer <brouer@...hat.com>
> ---

LGTM.

Acked-by: Andrii Nakryiko <andriin@...com>

>  net/bpf/test_run.c |    8 +++++---
>  1 file changed, 5 insertions(+), 3 deletions(-)
>

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