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From: Alexei Starovoitov <alexei.starovoitov@gmail.com>
To: Daniel Borkmann <daniel@iogearbox.net>
Cc: Rabin Vincent <rabin@rab.in>,
	davem@davemloft.net, netdev@vger.kernel.org, ast@kernel.org,
	linux-arm-kernel@lists.infradead.org, linux-mips@linux-mips.org,
	linuxppc-dev@lists.ozlabs.org, sparclinux@vger.kernel.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH] net: filter: make JITs zero A for SKF_AD_ALU_XOR_X
Date: Tue, 5 Jan 2016 09:43:10 -0800	[thread overview]
Message-ID: <20160105174309.GA83548@ast-mbp.thefacebook.com> (raw)
In-Reply-To: <568BF11F.1060507@iogearbox.net>

On Tue, Jan 05, 2016 at 05:36:47PM +0100, Daniel Borkmann wrote:
> On 01/05/2016 04:23 PM, Rabin Vincent wrote:
> >The SKF_AD_ALU_XOR_X ancillary is not like the other ancillary data
> >instructions since it XORs A with X while all the others replace A with
> >some loaded value.  All the BPF JITs fail to clear A if this is used as
> >the first instruction in a filter.  This was found using american fuzzy
> >lop.
> >
> >Add a helper to determine if A needs to be cleared given the first
> >instruction in a filter, and use this in the JITs.  Except for ARM, the
> >rest have only been compile-tested.
> >
> >Fixes: 3480593131e0 ("net: filter: get rid of BPF_S_* enum")
> >Signed-off-by: Rabin Vincent <rabin@rab.in>
> 
> Excellent catch, thanks a lot! The fix looks good to me and should
> go to -net tree.
> 
> Acked-by: Daniel Borkmann <daniel@iogearbox.net>

good catch indeed.
Classic bpf jits didn't have much love. Great to see this work.

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

  reply	other threads:[~2016-01-05 17:43 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-01-05 15:23 [PATCH] net: filter: make JITs zero A for SKF_AD_ALU_XOR_X Rabin Vincent
2016-01-05 16:00 ` Eric Dumazet
2016-01-05 16:03   ` Rabin Vincent
2016-01-05 16:37     ` Daniel Borkmann
2016-01-05 16:36 ` Daniel Borkmann
2016-01-05 17:43   ` Alexei Starovoitov [this message]
2016-01-06  5:44 ` David Miller

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