From: Michael Holzheu <holzheu@linux.vnet.ibm.com>
To: Daniel Borkmann <daniel@iogearbox.net>
Cc: ast@fb.com, naveen.n.rao@linux.vnet.ibm.com, davem@davemloft.net,
netdev@vger.kernel.org
Subject: Re: [PATCH bpf 1/5] bpf, s390x: do not reload skb pointers in non-skb context
Date: Tue, 9 Jan 2018 15:20:37 +0100 [thread overview]
Message-ID: <20180109152037.494db115@TP-holzheu> (raw)
In-Reply-To: <20171214200727.22230-2-daniel@iogearbox.net>
Am Thu, 14 Dec 2017 21:07:23 +0100
schrieb Daniel Borkmann <daniel@iogearbox.net>:
> The assumption of unconditionally reloading skb pointers on
> BPF helper calls where bpf_helper_changes_pkt_data() holds
> true is wrong. There can be different contexts where the
> BPF helper would enforce a reload such as in case of XDP.
> Here, we do have a struct xdp_buff instead of struct sk_buff
> as context, thus this will access garbage.
>
> JITs only ever need to deal with cached skb pointer reload
> when ld_abs/ind was seen, therefore guard the reload behind
> SEEN_SKB only. Tested on s390x.
Hello Daniel,
Sorry for the late answer - I have been on vacation up to now.
Thanks for fixing / testing this for s390x.
Michael
next prev parent reply other threads:[~2018-01-09 14:20 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-12-14 20:07 [PATCH bpf 0/5] Couple of BPF JIT fixes Daniel Borkmann
2017-12-14 20:07 ` [PATCH bpf 1/5] bpf, s390x: do not reload skb pointers in non-skb context Daniel Borkmann
2018-01-09 14:20 ` Michael Holzheu [this message]
2017-12-14 20:07 ` [PATCH bpf 2/5] bpf, ppc64: " Daniel Borkmann
2017-12-14 20:07 ` [PATCH bpf 3/5] bpf: guarantee r1 to be ctx in case of bpf_helper_changes_pkt_data Daniel Borkmann
2017-12-14 20:07 ` [PATCH bpf 4/5] bpf, sparc: fix usage of wrong reg for load_skb_regs after call Daniel Borkmann
2017-12-14 20:07 ` [PATCH bpf 5/5] bpf: add test case for ld_abs and helper changing pkt data Daniel Borkmann
2017-12-15 17:28 ` [PATCH bpf 0/5] Couple of BPF JIT fixes Alexei Starovoitov
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