Commit c51818d5 authored by Daniel Borkmann's avatar Daniel Borkmann Committed by David S. Miller

bpf, xdp, i40e: fix i40e_build_skb skb reserve and truesize

Using skb_reserve(skb, I40E_SKB_PAD + (xdp->data - xdp->data_hard_start))
is clearly wrong since I40E_SKB_PAD already points to the offset where
the original xdp->data was sitting since xdp->data_hard_start is defined
as xdp->data - i40e_rx_offset(rx_ring) where latter offsets to I40E_SKB_PAD
when build skb is used.

However, also before cc5b114d ("bpf, i40e: add meta data support")
this seems broken since bpf_xdp_adjust_head() helper could have been used
to alter headroom and enlarge / shrink the frame and with that the assumption
that the xdp->data remains unchanged does not hold and would push a bogus
packet to upper stack.

ixgbe got this right in 92470808 ("ixgbe: add XDP support for pass and
drop actions"). In any case, fix it by removing the I40E_SKB_PAD from both
skb_reserve() and truesize calculation.

Fixes: cc5b114d ("bpf, i40e: add meta data support")
Fixes: 0c8493d9 ("i40e: add XDP support for pass and drop actions")
Reported-by: default avatarKeith Busch <>
Reported-by: default avatarToshiaki Makita <>
Signed-off-by: default avatarDaniel Borkmann <>
Cc: Björn Töpel <>
Cc: John Fastabend <>
Tested-by: default avatarKeith Busch <>
Acked-by: default avatarJohn Fastabend <>
Acked-by: default avatarAlexander Duyck <>
Signed-off-by: default avatarJeff Kirsher <>
Signed-off-by: default avatarDavid S. Miller <>
parent d563e7a2
......@@ -2103,9 +2103,8 @@ static struct sk_buff *i40e_build_skb(struct i40e_ring *rx_ring,
unsigned int truesize = i40e_rx_pg_size(rx_ring) / 2;
unsigned int truesize = SKB_DATA_ALIGN(sizeof(struct skb_shared_info)) +
(xdp->data_end -
SKB_DATA_ALIGN(xdp->data_end -
struct sk_buff *skb;
......@@ -2124,7 +2123,7 @@ static struct sk_buff *i40e_build_skb(struct i40e_ring *rx_ring,
return NULL;
/* update pointers within the skb to store the data */
skb_reserve(skb, I40E_SKB_PAD + (xdp->data - xdp->data_hard_start));
skb_reserve(skb, xdp->data - xdp->data_hard_start);
__skb_put(skb, xdp->data_end - xdp->data);
if (metasize)
skb_metadata_set(skb, metasize);
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