{"cve":"CVE-2023-53523","nvd":{"published":"2025-10-01T12:15:56.747","modified":"2026-10-30T13:17:18.673","status":"Modified","description":"In the Linux kernel, the following vulnerability has been resolved:\n\ncan: gs_usb: fix time stamp counter initialization\n\nIf the gs_usb device driver is unloaded (or unbound) before the\ninterface is shut down, the USB stack first calls the struct\nusb_driver::disconnect and then the struct net_device_ops::ndo_stop\ncallback.\n\nIn gs_usb_disconnect() all pending bulk URBs are killed, i.e. no more\nRX'ed CAN frames are send from the USB device to the host. Later in\ngs_can_close() a reset control message is send to each CAN channel to\nremove the controller from the CAN bus. In this race window the USB\ndevice can still receive CAN frames from the bus and internally queue\nthem to be send to the host.\n\nAt least in the current version of the candlelight firmware, the queue\nof received CAN frames is not emptied during the reset command. After\nloading (or binding) the gs_usb driver, new URBs are submitted during\nthe struct net_device_ops::ndo_open callback and the candlelight\nfirmware starts sending its already queued CAN frames to the host.\n\nHowever, this scenario was not considered when implementing the\nhardware timestamp function. The cycle counter/time counter\ninfrastructure is set up (gs_usb_timestamp_init()) after the USBs are\nsubmitted, resulting in a NULL pointer dereference if\ntimecounter_cyc2time() (via the call chain:\ngs_usb_receive_bulk_callback() -> gs_usb_set_timestamp() ->\ngs_usb_skb_set_timestamp()) is called too early.\n\nMove the gs_usb_timestamp_init() function before the URBs are\nsubmitted to fix this problem.\n\nFor a comprehensive solution, we need to consider gs_usb devices with\nmore than 1 channel. The cycle counter/time counter infrastructure is\nsetup per channel, but the RX URBs are per device. Once gs_can_open()\nof _a_ channel has been called, and URBs have been submitted, the\ngs_usb_receive_bulk_callback() can be called for _all_ available\nchannels, even for channels that are not running, yet. As cycle\ncounter/time counter has not set up, this will again lead to a NULL\npointer dereference.\n\nConvert the cycle counter/time counter from a \"per channel\" to a \"per\ndevice\" functionality. Also set it up, before submitting any URBs to\nthe device.\n\nFurther in gs_usb_receive_bulk_callback(), don't process any URBs for\nnot started CAN channels, only resubmit the URB.","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","score":5.5},"cwes":["CWE-476"],"references":["https://git.kernel.org/stable/c/210a8cffc9c1b044281c0a868485c870c9c11374","https://git.kernel.org/stable/c/5886e4d5ecec3e22844efed90b2dd383ef804b3a","https://git.kernel.org/stable/c/7d470bb955210eb7d31f14427b48058487d42355"],"products":["linux:linux_kernel"],"source":"nvd","synced_at":"2026-10-30T13:47:47.119061695+00:00"},"epss":{"cve":"CVE-2023-53523","score":0.0013,"percentile":0.02635,"date":"2026-10-30"},"kev":null,"osv":[],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}