CVE-2026-80998: net: bnxt: ring the doorbell when SW USO exits early

CVE-2026-80998: net: bnxt: ring the doorbell when SW USO exits early

[Greg Kroah-Hartman]

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

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

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

net: bnxt: ring the doorbell when SW USO exits early

When a burst of packets is handed down to the driver, the driver defers
the doorbell to the end by setting txr->kick_pending = 1. The normal TX
path handles this, but the SW USO path can miss it if it returns
early.

If bnxt_sw_udp_gso_xmit runs but returns early with NETDEV_TX_BUSY and
txr->kick_pending was previously set to 1, then the TX queue can
stall because the driver wrote some BDs but never wrote the doorbell.
The device won't know to do the TX which would generate the completion
that would wake the queue back up.

Simplify bnxt_sw_udp_gso_xmit to set txr->kick_pending in its success
case and check the flag on return. The added check after
bnxt_sw_udp_gso_xmit returns ensures that any pending doorbells are
written handling both successful USO and any early returns, which
prevents the TX queue stall mentioned above.

This TX queue stall was observed on a production system with a netdev TX
watchdog informing about the queue stall.

The Linux kernel CVE team has assigned CVE-2026-80998 to this issue.


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

	Issue introduced in 7.1 with commit cc5d90667db81474ed7a92a1b2fa3daec5559307 and fixed in 7.2.4 with commit 48d1c9665db6e3d4aeca62eb669377162ebc6fdf
	Issue introduced in 7.1 with commit cc5d90667db81474ed7a92a1b2fa3daec5559307 and fixed in 7.3-rc1 with commit 4e15e89faac9f308baeb01f46c13a051814d2449

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-2026-80998
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/broadcom/bnxt/bnxt.c
	drivers/net/ethernet/broadcom/bnxt/bnxt_gso.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/48d1c9665db6e3d4aeca62eb669377162ebc6fdf
	https://git.kernel.org/stable/c/4e15e89faac9f308baeb01f46c13a051814d2449