[PATCH net] octeontx2-pf: fix XDP frames freed as skbs on interface down

[PATCH net] octeontx2-pf: fix XDP frames freed as skbs on interface down

[Nicolai Buchwitz]

On interface down, the TX completion cleanup also runs on the XDP
queues, but treats the pending xdp_frames as skbs. Freeing them with
dev_kfree_skb_any() corrupts page pool memory.

This happens when XDP_TX or redirected packets are still in flight on
ifdown, or when the XDP program is replaced.

Fixes: 94c80f748873 ("octeontx2-pf: use xdp_return_frame() to free xdp buffers")
Signed-off-by: Nicolai Buchwitz <nb@tipi-net.de>
---
Pre-existing bug, flagged by the clashiko review of my ipsec transmit
fixes for this driver [1], which seems reasonable (and fixable) to me.

The other pre-existing findings there (e.g. the SA lifetime in
cn10k_ipsec_del_state()) may be worth fixing too, but I'll leave those
to the maintainers.

Compile-tested only, I have no octeontx2 hardware.

[1] https://netdev-ai.bots.linux.dev/sashiko/#/patchset/20261027-nb-otx2-ipsec-tx-fixes-net-v1-0-2114c4f10c36%40tipi-net.de
---
 drivers/net/ethernet/marvell/octeontx2/nic/otx2_txrx.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/net/ethernet/marvell/octeontx2/nic/otx2_txrx.c b/drivers/net/ethernet/marvell/octeontx2/nic/otx2_txrx.c
index 90af9b9044aa0..e3b07e5335fb8 100644
--- a/drivers/net/ethernet/marvell/octeontx2/nic/otx2_txrx.c
+++ b/drivers/net/ethernet/marvell/octeontx2/nic/otx2_txrx.c
@@ -1332,6 +1332,7 @@ void otx2_cleanup_tx_cqes(struct otx2_nic *pfvf, struct otx2_cq_queue *cq)
 	struct nix_cqe_tx_s *cqe;
 	struct netdev_queue *txq;
 	int processed_cqe = 0;
+	int xsk_frames = 0;
 	struct sg_list *sg;
 	int qidx;
 
@@ -1348,6 +1349,10 @@ void otx2_cleanup_tx_cqes(struct otx2_nic *pfvf, struct otx2_cq_queue *cq)
 
 		if (!cqe)
 			continue;
+		if (cq->cq_type == CQ_XDP) {
+			otx2_xdp_snd_pkt_handler(pfvf, sq, cqe, &xsk_frames);
+			continue;
+		}
 		sg = &sq->sg[cqe->comp.sqe_id];
 		skb = (struct sk_buff *)sg->skb;
 		if (skb) {

---
base-commit: d8a4f4c59da52b7c31ae337243b8473a19a3f819
change-id: 20261028-nb-otx2-xdp-cqe-cleanup-net-5810d40e1d30

Best regards,
--  
Nicolai Buchwitz <nb@tipi-net.de>

Re: [PATCH net] octeontx2-pf: fix XDP frames freed as skbs on interface down

[sashiko-bot]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Medium] octeontx2-pf: missing xsk_tx_completed() call in otx2_cleanup_tx_cqes()
--

commit 40946781f760bef2ef894a136c752dbc204d2650
Author: Nicolai Buchwitz <nb@tipi-net.de>

octeontx2-pf: fix XDP frames freed as skbs on interface down

This commit updates otx2_cleanup_tx_cqes() to handle CQ_XDP completions via
otx2_xdp_snd_pkt_handler() instead of freeing pending xdp_frame pointers with
dev_kfree_skb_any() during interface teardown or XDP program replacement.

> diff --git a/drivers/net/ethernet/marvell/octeontx2/nic/otx2_txrx.c b/drivers/net/ethernet/marvell/octeontx2/nic/otx2_txrx.c
> index 90af9b9044aa0..e3b07e5335fb8 100644
> --- a/drivers/net/ethernet/marvell/octeontx2/nic/otx2_txrx.c
> +++ b/drivers/net/ethernet/marvell/octeontx2/nic/otx2_txrx.c
> @@ -1332,6 +1332,7 @@ void otx2_cleanup_tx_cqes(struct otx2_nic *pfvf, struct otx2_cq_queue *cq)
>  	struct nix_cqe_tx_s *cqe;
>  	struct netdev_queue *txq;
>  	int processed_cqe = 0;
> +	int xsk_frames = 0;
>  	struct sg_list *sg;
>  	int qidx;
>  
> @@ -1348,6 +1349,10 @@ void otx2_cleanup_tx_cqes(struct otx2_nic *pfvf, struct otx2_cq_queue *cq)
>  
>  		if (!cqe)
>  			continue;
> +		if (cq->cq_type == CQ_XDP) {
> +			otx2_xdp_snd_pkt_handler(pfvf, sq, cqe, &xsk_frames);
> +			continue;
> +		}

[Severity: Medium]
Does otx2_cleanup_tx_cqes() also need to pass xsk_frames to
xsk_tx_completed() after draining the loop?

When AF_XDP zero-copy TX descriptors are reaped in
drivers/net/ethernet/marvell/octeontx2/nic/otx2_txrx.c:

otx2_xdp_snd_pkt_handler() {
	...
	sg = &sq->sg[snd_comp->sqe_id];
	if (sg->flags & OTX2_AF_XDP_FRAME) {
		(*xsk_frames)++;
		return;
	}
	...
}

the handler only increments xsk_frames and relies on the caller to publish
the completions to sq->xsk_pool, as done in the normal NAPI completion path via
otx2_tx_napi_handler() -> otx2_zc_submit_pkts():

	if (*xsk_frames)
		xsk_tx_completed(xsk_pool, *xsk_frames);

In otx2_cleanup_tx_cqes(), xsk_frames is accumulated across the while
(cq->pend_cqe) loop, but it is never read afterwards. If an interface with an
active AF_XDP zero-copy TX socket is brought down or has its XDP program
replaced while AF_XDP TX completions are pending in a CQ_XDP queue, wouldn't
those completion ring entries be leaked without calling
xsk_tx_completed(sq->xsk_pool, xsk_frames)?

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20261030-nb-otx2-xdp-cqe-cleanup-net-v1-1-710635c0f504@tipi-net.de?part=1