| From | Greg Kroah-Hartman <> | Subject | [PATCH 4.19 497/639] net: fix bpf_xdp_adjust_head regression for generic-XDP | Date | Fri, 24 Jan 2020 10:31:07 +0100 |
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From: Jesper Dangaard Brouer <brouer@redhat.com>
[ Upstream commit 065af355470519bd184019a93ac579f22b036045 ]
When generic-XDP was moved to a later processing step by commit 458bf2f224f0 ("net: core: support XDP generic on stacked devices.") a regression was introduced when using bpf_xdp_adjust_head.
The issue is that after this commit the skb->network_header is now changed prior to calling generic XDP and not after. Thus, if the header is changed by XDP (via bpf_xdp_adjust_head), then skb->network_header also need to be updated again. Fix by calling skb_reset_network_header().
Fixes: 458bf2f224f0 ("net: core: support XDP generic on stacked devices.") Reported-by: Brandon Cazander <brandon.cazander@multapplied.net> Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Sasha Levin <sashal@kernel.org> --- net/core/dev.c | 15 ++++++++++----- 1 file changed, 10 insertions(+), 5 deletions(-)
diff --git a/net/core/dev.c b/net/core/dev.c index 935fe158cfaff..73ebacabfde8d 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -4349,12 +4349,17 @@ static u32 netif_receive_generic_xdp(struct sk_buff *skb, act = bpf_prog_run_xdp(xdp_prog, xdp); + /* check if bpf_xdp_adjust_head was used */ off = xdp->data - orig_data; - if (off > 0) - __skb_pull(skb, off); - else if (off < 0) - __skb_push(skb, -off); - skb->mac_header += off; + if (off) { + if (off > 0) + __skb_pull(skb, off); + else if (off < 0) + __skb_push(skb, -off); + + skb->mac_header += off; + skb_reset_network_header(skb); + } /* check if bpf_xdp_adjust_tail was used. it can only "shrink" * pckt. -- 2.20.1
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