Re: [Intel-wired-lan] [net, v2, 02/12] idpf: skip deallocating bufq_sets from rx_qgrp if it is NULL

Hay, Joshua A
2026-03-02T22:08:20Z

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>
> For local reproduction steps see https://netdev-ai.bots.linux.dev/ai-local.html
> ---
> idpf: skip deallocating bufq_sets from rx_qgrp if it is NULL
>
> This patch adds a NULL check for rx_qgrp->splitq.bufq_sets to prevent
> kernel panic when idpf_rxq_group_alloc() fails during initialization and
> the error path calls idpf_rxq_sw_queue_rel(). The panic was occurring
> during device opening when adding to a bonding interface.
>
> > diff --git a/drivers/net/ethernet/intel/idpf/idpf_txrx.c
> b/drivers/net/ethernet/intel/idpf/idpf_txrx.c
> > index 761a77510467..59aafadae3d0 100644
> > --- a/drivers/net/ethernet/intel/idpf/idpf_txrx.c
> > +++ b/drivers/net/ethernet/intel/idpf/idpf_txrx.c
> > @@ -1341,6 +1341,9 @@ static void idpf_txq_group_rel(struct
> idpf_q_vec_rsrc *rsrc)
> > */
> > static void idpf_rxq_sw_queue_rel(struct idpf_rxq_group *rx_qgrp)
> > {
> > + if (!rx_qgrp->splitq.bufq_sets)
> > + return;
> > +
> > for (unsigned int i = 0; i < rx_qgrp->splitq.num_bufq_sets; i++) {
> > struct idpf_bufq_set *bufq_set = &rx_qgrp-
> >splitq.bufq_sets[i];
> >
> > for (unsigned int j = 0; j < bufq_set->num_refillqs; j++) {
> > kfree(bufq_set->refillqs[j].ring);
> > bufq_set->refillqs[j].ring = NULL;
> ^^^^^^
> This patch adds a NULL check for bufq_sets, but does the same issue
> exist for refillqs?
>
> Looking at idpf_rxq_group_alloc() in the same file, it first sets
> bufq_set->num_refillqs to a non-zero value, then attempts to allocate
> refillqs:
>
> idpf_rxq_group_alloc() {
> ...
> bufq_set->num_refillqs = num_rxq;
> bufq_set->refillqs = kcalloc(bufq_set->num_refillqs,
> sizeof(struct idpf_sw_queue),
> GFP_KERNEL);
> if (!bufq_set->refillqs) {
> err = -ENOMEM;
> goto err_alloc;
> }
> ...
> }
>
> If this allocation fails, bufq_set->refillqs is NULL but
> bufq_set->num_refillqs is non-zero. The error path calls
> idpf_rxq_sw_queue_rel() which now passes the bufq_sets check but then
> dereferences bufq_set->refillqs[j].ring in the inner loop.
>
> The inner loop condition (j < bufq_set->num_refillqs) would be true,
> causing the same NULL pointer dereference the patch is meant to prevent.
>
> Would this need a similar check before the inner loop, similar to the
> bufq_sets check added in this patch?

This is a valid bug, but we can fix it in a different way. Will send a follow up patch shortly.

Thanks!
Josh