bpf, s390x: do not reload skb pointers in non-skb context

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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.

Fixes: 9db7f2b818 ("s390/bpf: recache skb->data/hlen for skb_vlan_push/pop")
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Cc: Michael Holzheu <holzheu@linux.vnet.ibm.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

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Daniel Borkmann 2017-12-14 21:07:23 +01:00 • committed by Alexei Starovoitov

parent 2d17d8d79e

commit 6d59b7dbf7

1 changed files with 5 additions and 6 deletions

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arch/s390/net/bpf_jit_comp.c

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