Re: [PATCH net-next] x86: bpf_jit_comp: secure bpf jit againstspraying attacks

From: David Miller
Date: Mon May 20 2013 - 02:56:21 EST

From: Eric Dumazet <eric.dumazet@xxxxxxxxx>
Date: Fri, 17 May 2013 19:37:03 -0700

> From: Eric Dumazet <edumazet@xxxxxxxxxx>
> hpa bringed into my attention some security related issues
> with BPF JIT on x86.
> This patch makes sure the bpf generated code is marked read only,
> as other kernel text sections.
> It also splits the unused space (we vmalloc() and only use a fraction of
> the page) in two parts, so that the generated bpf code not starts at a
> known offset in the page, but a pseudo random one.
> Refs:
> Reported-by: H. Peter Anvin <hpa@xxxxxxxxx>
> Signed-off-by: Eric Dumazet <edumazet@xxxxxxxxxx>

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