CVE-2023-53523

can: gs_usb: fix time stamp counter initialization

Published Oct 1, 2025 CVSS 3.1 · 5.5 Medium EPSS < 1% KEV · Not listed
Description
In the Linux kernel, the following vulnerability has been resolved:

can: gs_usb: fix time stamp counter initialization

If the gs_usb device driver is unloaded (or unbound) before the
interface is shut down, the USB stack first calls the struct
usb_driver::disconnect and then the struct net_device_ops::ndo_stop
callback.

In gs_usb_disconnect() all pending bulk URBs are killed, i.e. no more
RX'ed CAN frames are send from the USB device to the host. Later in
gs_can_close() a reset control message is send to each CAN channel to
remove the controller from the CAN bus. In this race window the USB
device can still receive CAN frames from the bus and internally queue
them to be send to the host.

At least in the current version of the candlelight firmware, the queue
of received CAN frames is not emptied during the reset command. After
loading (or binding) the gs_usb driver, new URBs are submitted during
the struct net_device_ops::ndo_open callback and the candlelight
firmware starts sending its already queued CAN frames to the host.

However, this scenario was not considered when implementing the
hardware timestamp function. The cycle counter/time counter
infrastructure is set up (gs_usb_timestamp_init()) after the USBs are
submitted, resulting in a NULL pointer dereference if
timecounter_cyc2time() (via the call chain:
gs_usb_receive_bulk_callback() -> gs_usb_set_timestamp() ->
gs_usb_skb_set_timestamp()) is called too early.

Move the gs_usb_timestamp_init() function before the URBs are
submitted to fix this problem.

For a comprehensive solution, we need to consider gs_usb devices with
more than 1 channel. The cycle counter/time counter infrastructure is
setup per channel, but the RX URBs are per device. Once gs_can_open()
of _a_ channel has been called, and URBs have been submitted, the
gs_usb_receive_bulk_callback() can be called for _all_ available
channels, even for channels that are not running, yet. As cycle
counter/time counter has not set up, this will again lead to a NULL
pointer dereference.

Convert the cycle counter/time counter from a "per channel" to a "per
device" functionality. Also set it up, before submitting any URBs to
the device.

Further in gs_usb_receive_bulk_callback(), don't process any URBs for
not started CAN channels, only resubmit the URB.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

Source ID Title
EUVD EUVD EUVD-2025-31889
History
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Type Values Removed Values Added
Weaknesses CWE-476
CPEs cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:6.5:rc1:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:6.5:rc2:*:*:*:*:*:*
Metrics cvssV3_1

{'score': 7.0, 'vector': 'CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H'}

cvssV3_1

{'score': 5.5, 'vector': 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H'}

Type Values Removed Values Added
First Time appeared Linux
Linux linux Kernel
Vendors & Products Linux
Linux linux Kernel
Type Values Removed Values Added
References
Metrics threat_severity

None

cvssV3_1

{'score': 7.0, 'vector': 'CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H'}

threat_severity

Important

Type Values Removed Values Added
Description In the Linux kernel, the following vulnerability has been resolved: can: gs_usb: fix time stamp counter initialization If the gs_usb device driver is unloaded (or unbound) before the interface is shut down, the USB stack first calls the struct usb_driver::disconnect and then the struct net_device_ops::ndo_stop callback. In gs_usb_disconnect() all pending bulk URBs are killed, i.e. no more RX'ed CAN frames are send from the USB device to the host. Later in gs_can_close() a reset control message is send to each CAN channel to remove the controller from the CAN bus. In this race window the USB device can still receive CAN frames from the bus and internally queue them to be send to the host. At least in the current version of the candlelight firmware, the queue of received CAN frames is not emptied during the reset command. After loading (or binding) the gs_usb driver, new URBs are submitted during the struct net_device_ops::ndo_open callback and the candlelight firmware starts sending its already queued CAN frames to the host. However, this scenario was not considered when implementing the hardware timestamp function. The cycle counter/time counter infrastructure is set up (gs_usb_timestamp_init()) after the USBs are submitted, resulting in a NULL pointer dereference if timecounter_cyc2time() (via the call chain: gs_usb_receive_bulk_callback() -> gs_usb_set_timestamp() -> gs_usb_skb_set_timestamp()) is called too early. Move the gs_usb_timestamp_init() function before the URBs are submitted to fix this problem. For a comprehensive solution, we need to consider gs_usb devices with more than 1 channel. The cycle counter/time counter infrastructure is setup per channel, but the RX URBs are per device. Once gs_can_open() of _a_ channel has been called, and URBs have been submitted, the gs_usb_receive_bulk_callback() can be called for _all_ available channels, even for channels that are not running, yet. As cycle counter/time counter has not set up, this will again lead to a NULL pointer dereference. Convert the cycle counter/time counter from a "per channel" to a "per device" functionality. Also set it up, before submitting any URBs to the device. Further in gs_usb_receive_bulk_callback(), don't process any URBs for not started CAN channels, only resubmit the URB.
Title can: gs_usb: fix time stamp counter initialization
References
Weaknesses

Sources

Status
PUBLISHED
Assigner
Linux
Published
Updated
Nov 5, 2026, 8:31 PM
Reserved
Oct 1, 2025, 11:39 AM
Status
Modified
Published
Oct 1, 2025, 12:15 PM
Modified
Nov 5, 2026, 9:17 PM
Severity
Important
Public date
Oct 1, 2025, 12:00 AM