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xsk: tighten UMEM headroom validation to account for tailroom and min frame

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The current headroom validation in xdp_umem_reg() could leave us with
insufficient space dedicated to even receive minimum-sized ethernet
frame. Furthermore if multi-buffer would come to play then
skb_shared_info stored at the end of XSK frame would be corrupted.

HW typically works with 128-aligned sizes so let us provide this value
as bare minimum.

Multi-buffer setting is known later in the configuration process so
besides accounting for 128 bytes, let us also take care of tailroom space
upfront.

Reviewed-by: Björn Töpel <bjorn@kernel.org>
Acked-by: Stanislav Fomichev <sdf@fomichev.me>
Fixes: 99e3a236dd ("xsk: Add missing check on user supplied headroom size")
Signed-off-by: Maciej Fijalkowski <maciej.fijalkowski@intel.com>
Link: https://patch.msgid.link/20260402154958.562179-2-maciej.fijalkowski@intel.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Maciej Fijalkowski
2026-04-02 17:49:51 +02:00
committed by Jakub Kicinski
parent 1caa871bb0
commit a315e022a7
1 changed files with 2 additions and 1 deletions
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3
net/xdp/xdp_umem.c
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@@ -203,7 +203,8 @@ static int xdp_umem_reg(struct xdp_umem *umem, struct xdp_umem_reg *mr)
if (!unaligned_chunks && chunks_rem)
return -EINVAL;
if (headroom >= chunk_size - XDP_PACKET_HEADROOM)
if (headroom > chunk_size - XDP_PACKET_HEADROOM -
SKB_DATA_ALIGN(sizeof(struct skb_shared_info)) - 128)
return -EINVAL;
if (mr->flags & XDP_UMEM_TX_METADATA_LEN) {