CVE-2026-98617: eth: fbnic: use the Rx queue napi pointer to find the napi vector

CVE-2026-98617: eth: fbnic: use the Rx queue napi pointer to find the napi vector

[Greg Kroah-Hartman]

From: Greg Kroah-Hartman <gregkh@kernel.org>

Description
===========

In the Linux kernel, the following vulnerability has been resolved:

eth: fbnic: use the Rx queue napi pointer to find the napi vector

The queue management ndos pick the napi vector for an Rx queue with:
	nv = fbn->napi[idx % fbn->num_napi];

The issue is this is only correct in the cases where there are no
standalone Tx vectors. In those cases we were allocating the Tx vectors
first and then the Rx so the queues would be pointing to Tx NAPI vectors
instead of the Rx ones.

The mapping the ndos want is already recorded.  fbnic_set_netif_napi()
publishes it with netif_queue_set_napi(), which stores the napi pointer
in netdev_rx_queue.napi, and fbnic_reset_netif_napi() clears it again.
Both run under the netdev instance lock that the queue management ndos
also hold, so the pointer can be read directly.

Use it and drop the divide.  The pointer is NULL exactly while the
datapath is down, so fbnic_queue_mem_alloc() can reject that case rather
than reaching into freed state: netdev_rx_queue_restart() calls it
before it tests netif_running(), and fbnic_pm_suspend() leaves
netif_running() true across a PCIe recovery that never completes, so a
queue restart can arrive after fbnic_stop() has freed the rings and the
vectors.  fbnic_stop() clears the association in
fbnic_reset_netif_queues() before fbnic_free_napi_vectors(), so the
NULL is always published first.  fbnic_queue_start() and
fbnic_queue_stop() need no check of their own, as
netdev_rx_queue_reconfig() only reaches them once fbnic_queue_mem_alloc()
has succeeded under the same instance lock.

The Linux kernel CVE team has assigned CVE-2026-98617 to this issue.


Affected and fixed versions
===========================

	Issue introduced in 6.18 with commit da43127a8edc7498cce7b2554533f4027c618933 and fixed in 7.2.9 with commit 1fb569cf3bf97e552f465b2c719e36b48ae7c18b
	Issue introduced in 6.18 with commit da43127a8edc7498cce7b2554533f4027c618933 and fixed in 7.3-rc5 with commit b5d9e9d4d0c13bc8b60d8d97e7a07fb25fea639e

Please see https://www.kernel.org for a full list of currently supported
kernel versions by the kernel community.

Unaffected versions might change over time as fixes are backported to
older supported kernel versions.  The official CVE entry at
	https://cve.org/CVERecord/?id=CVE-2026-98617
will be updated if fixes are backported, please check that for the most
up to date information about this issue.


Affected files
==============

The file(s) affected by this issue are:
	drivers/net/ethernet/meta/fbnic/fbnic_txrx.c


Mitigation
==========

The Linux kernel CVE team recommends that you update to the latest
stable kernel version for this, and many other bugfixes.  Individual
changes are never tested alone, but rather are part of a larger kernel
release.  Cherry-picking individual commits is not recommended or
supported by the Linux kernel community at all.  If however, updating to
the latest release is impossible, the individual changes to resolve this
issue can be found at these commits:
	https://git.kernel.org/stable/c/1fb569cf3bf97e552f465b2c719e36b48ae7c18b
	https://git.kernel.org/stable/c/b5d9e9d4d0c13bc8b60d8d97e7a07fb25fea639e