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

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Date:   Tue, 19 May 2020 19:22:08 +0200
From:   Daniel Borkmann <daniel@...earbox.net>
To:     Jesper Dangaard Brouer <brouer@...hat.com>
Cc:     netdev@...r.kernel.org, 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 5/18/20 3:05 PM, Jesper Dangaard Brouer 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>

Applied, thanks!