netdev - Re: [PATCH 2/3] powerpc: bpf: flush the entire JIT buffer

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Message-ID: <58795AC4.2070302@iogearbox.net>
Date:   Fri, 13 Jan 2017 23:55:00 +0100
From:   Daniel Borkmann <daniel@...earbox.net>
To:     "Naveen N. Rao" <naveen.n.rao@...ux.vnet.ibm.com>,
        mpe@...erman.id.au
CC:     linuxppc-dev@...ts.ozlabs.org, netdev@...r.kernel.org, ast@...com,
        davem@...emloft.net
Subject: Re: [PATCH 2/3] powerpc: bpf: flush the entire JIT buffer

On 01/13/2017 06:10 PM, Naveen N. Rao wrote:
> With bpf_jit_binary_alloc(), we allocate at a page granularity and fill
> the rest of the space with illegal instructions to mitigate BPF spraying
> attacks, while having the actual JIT'ed BPF program at a random location
> within the allocated space. Under this scenario, it would be better to
> flush the entire allocated buffer rather than just the part containing
> the actual program. We already flush the buffer from start to the end of
> the BPF program. Extend this to include the illegal instructions after
> the BPF program.
>
> Signed-off-by: Naveen N. Rao <naveen.n.rao@...ux.vnet.ibm.com>

Acked-by: Daniel Borkmann <daniel@...earbox.net>