CVE-2025-39854

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

ice: fix NULL access of tx->in_use in ice_ll_ts_intr

Recent versions of the E810 firmware have support for an extra interrupt to handle report of the "low latency" Tx timestamps coming from the specialized low latency firmware interface. Instead of polling the registers, software can wait until the low latency interrupt is fired.

This logic makes use of the Tx timestamp tracking structure, ice_ptp_tx, as it uses the same "ready" bitmap to track which Tx timestamps complete.

Unfortunately, the ice_ll_ts_intr() function does not check if the tracker is initialized before its first access. This results in NULL dereference or use-after-free bugs similar to the issues fixed in the ice_ptp_ts_irq() function.

Fix this by only checking the in_use bitmap (and other fields) if the tracker is marked as initialized. The reset flow will clear the init field under lock before it tears the tracker down, thus preventing any use-after-free or NULL access.

This vulnerability is rated as Moderate impact for Red Hat Enterprise Linux because triggering the flaw requires specific Intel E800 series hardware running firmware with low-latency timestamping support, substantially limiting exposure. In typical deployments, exploitation necessitates local administrative privileges to interact with network device configurations or initiate driver reset cycles, resulting in a denial of service through a kernel crash rather than unauthorized code execution or data leakage. Systems that do not use Intel ice hardware or that run older enterprise releases where this functionality is not present remain unaffected.

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.