CVE-2026-98489

/// Technical description

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

net: atl1c: fix soft lockup on out-of-range tpd_cons read

The hardware can report an out-of-range tpd_cons (seen as 0xffff)

while the PCIe link/MAC is resetting. An out-of-range value can

never be reached and the loop below would spin forever. To avoid

a soft lockup treat it as "nothing new to clean" instead.

Reproduced on two machines, same NIC (Qualcomm Atheros AR8151 v2.0,

4-port), triggered by rebooting a Mikrotik CCR2004 PCIe card that

the ports are directly linked to:

- Ubuntu 26.04.1 LTS, kernel 7.0.0-31-generic. The link-flap

precursor, before the lockup was captured with a full trace

elsewhere:

atl1c 0000:05:00.0 enp5s0f0: NETDEV WATCHDOG: CPU: 4: transmit queue 2 timed out 489984 ms

atl1c 0000:05:00.0: MAC state machine can't be idle since disabled for 10ms second

atl1c 0000:05:00.0: atl1c: enp5s0f0 NIC Link is Up<65535 Mbps Full Duplex>

65535 (0xffff) here is the same value tpd_cons r

/// Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

/// References