linux-cve-announce - CVE-2025-39855: ice: fix NULL access of tx->in_use in ice_ptp_ts

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Message-ID: <2025091905-CVE-2025-39855-fd73@gregkh>
Date: Fri, 19 Sep 2025 17:28:19 +0200
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...nel.org>
Subject: CVE-2025-39855: ice: fix NULL access of tx->in_use in ice_ptp_ts_irq

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

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

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

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

The E810 device has support for a "low latency" firmware interface to
access and read the Tx timestamps. This interface does not use the standard
Tx timestamp logic, due to the latency overhead of proxying sideband
command requests over the firmware AdminQ.

The logic still 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_ptp_ts_irq() 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 following:

[245977.278756] BUG: kernel NULL pointer dereference, address: 0000000000000000
[245977.278774] RIP: 0010:_find_first_bit+0x19/0x40
[245977.278796] Call Trace:
[245977.278809]  ? ice_misc_intr+0x364/0x380 [ice]

This can occur if a Tx timestamp interrupt races with the driver reset
logic.

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.

The Linux kernel CVE team has assigned CVE-2025-39855 to this issue.

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

	Issue introduced in 6.15 with commit f9472aaabd1f38954938838a1146db4855ad88e8 and fixed in 6.16.6 with commit 1467a873b20110263cc9c93de99335d139c11e16
	Issue introduced in 6.15 with commit f9472aaabd1f38954938838a1146db4855ad88e8 and fixed in 6.17-rc5 with commit 403bf043d9340196e06769065169df7444b91f7a

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-2025-39855
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/intel/ice/ice_ptp.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/1467a873b20110263cc9c93de99335d139c11e16
	https://git.kernel.org/stable/c/403bf043d9340196e06769065169df7444b91f7a