# Re: \[PATCH 2/3\] powerpc: bpf: flush the entire JIT buffer

- From: Alexei Starovoitov \<hidden\>
- Date: 2017-01-13 20:11:02 
- List: netdev
- Page: https://ratatoskr.run/netdev/2017/01/9494670
- Thread: https://ratatoskr.run/linuxppc-dev/2017/01/9494664/t.md

```text
On Fri, Jan 13, 2017 at 10:40:01PM +0530, 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 <redacted>

Acked-by: Alexei Starovoitov <ast@kernel.org>
```