CVE-2025-37897

Published May 20, 2025

Last updated a year ago

Overview

Description
In the Linux kernel, the following vulnerability has been resolved: wifi: plfxlc: Remove erroneous assert in plfxlc_mac_release plfxlc_mac_release() asserts that mac->lock is held. This assertion is incorrect, because even if it was possible, it would not be the valid behaviour. The function is used when probe fails or after the device is disconnected. In both cases mac->lock can not be held as the driver is not working with the device at the moment. All functions that use mac->lock unlock it just after it was held. There is also no need to hold mac->lock for plfxlc_mac_release() itself, as mac data is not affected, except for mac->flags, which is modified atomically. This bug leads to the following warning: ================================================================ WARNING: CPU: 0 PID: 127 at drivers/net/wireless/purelifi/plfxlc/mac.c:106 plfxlc_mac_release+0x7d/0xa0 Modules linked in: CPU: 0 PID: 127 Comm: kworker/0:2 Not tainted 6.1.124-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024 Workqueue: usb_hub_wq hub_event RIP: 0010:plfxlc_mac_release+0x7d/0xa0 drivers/net/wireless/purelifi/plfxlc/mac.c:106 Call Trace: <TASK> probe+0x941/0xbd0 drivers/net/wireless/purelifi/plfxlc/usb.c:694 usb_probe_interface+0x5c0/0xaf0 drivers/usb/core/driver.c:396 really_probe+0x2ab/0xcb0 drivers/base/dd.c:639 __driver_probe_device+0x1a2/0x3d0 drivers/base/dd.c:785 driver_probe_device+0x50/0x420 drivers/base/dd.c:815 __device_attach_driver+0x2cf/0x510 drivers/base/dd.c:943 bus_for_each_drv+0x183/0x200 drivers/base/bus.c:429 __device_attach+0x359/0x570 drivers/base/dd.c:1015 bus_probe_device+0xba/0x1e0 drivers/base/bus.c:489 device_add+0xb48/0xfd0 drivers/base/core.c:3696 usb_set_configuration+0x19dd/0x2020 drivers/usb/core/message.c:2165 usb_generic_driver_probe+0x84/0x140 drivers/usb/core/generic.c:238 usb_probe_device+0x130/0x260 drivers/usb/core/driver.c:293 really_probe+0x2ab/0xcb0 drivers/base/dd.c:639 __driver_probe_device+0x1a2/0x3d0 drivers/base/dd.c:785 driver_probe_device+0x50/0x420 drivers/base/dd.c:815 __device_attach_driver+0x2cf/0x510 drivers/base/dd.c:943 bus_for_each_drv+0x183/0x200 drivers/base/bus.c:429 __device_attach+0x359/0x570 drivers/base/dd.c:1015 bus_probe_device+0xba/0x1e0 drivers/base/bus.c:489 device_add+0xb48/0xfd0 drivers/base/core.c:3696 usb_new_device+0xbdd/0x18f0 drivers/usb/core/hub.c:2620 hub_port_connect drivers/usb/core/hub.c:5477 [inline] hub_port_connect_change drivers/usb/core/hub.c:5617 [inline] port_event drivers/usb/core/hub.c:5773 [inline] hub_event+0x2efe/0x5730 drivers/usb/core/hub.c:5855 process_one_work+0x8a9/0x11d0 kernel/workqueue.c:2292 worker_thread+0xa47/0x1200 kernel/workqueue.c:2439 kthread+0x28d/0x320 kernel/kthread.c:376 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295 </TASK> ================================================================ Found by Linux Verification Center (linuxtesting.org) with Syzkaller.
Source
416baaa9-dc9f-4396-8d5f-8c081fb06d67
NVD status
Analyzed
Products
linux_kernel, debian_linux

Risk scores

CVSS 3.1

Type
Primary
Base score
5.5
Impact score
3.6
Exploitability score
1.8
Vector string
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Severity
MEDIUM

Weaknesses

nvd@nist.gov
CWE-617

Social media

Hype score
Not currently trending

Configurations

  1. In the Linux kernel, the following vulnerability has been resolved: cgroup: Avoid iteration of dying tasks with zero refcount The commit 260fbcb92bbea ("cgroup: Move dying_tasks cleanup from cgroup_task_release() to cgroup_task_free()") extended the lifetime of tasks on the dying_tasks list. The iterators have provision to go through dying_tasks because of dying threadgroup leaders or explicit CSS_TASK_ITER_WITH_DEAD, however, it was expected that such tasks can obtain a new reference (that is possible before cgroup_task_release()/put_task_struct_rcu_user()). The tasks after cgroup_task_release() and before cgroup_task_free() are subject to race when they may or may not have ->usage count > 0. The race window is between css_task_iter_next() invocations when css_set_lock is released and we may arrive at a new ->task_pos. The iterator should not attempt to resurrect tasks whose ->usage count dropped to zero. (When that happens, __put_task_struct_rcu_cb() is already imminent and the returned task_struct would could be used after free.) As for the fix, we cannot simply check the signal->live count of a task on the dying list because that won't distinguish regular zombies waiting to be reaped from RCU remnant tasks that are going to be free'd. Therefore add an extra check to rule out ->usage==0 tasks from any iteration. The repeat: loop in css_task_iter_advance() doesn't consider ->usage count, so add a new loop to css_task_iter_next() to skip de-used tasks on the dying_list. Rough illustration of the possible race R (reader of cgroup.procs) T (thread) L (group leader) --------------------------------- -------------------------------- -------------------------------- L exits, signal->live > 0 cgroup_task_dead(L) css_set_skip_task_iters() // skips only cset->tasks list_add_tail(&L->cg_list, &cset->dying_tasks) css_task_iter_next() take css_set_lock css_task_iter_advance() leader && signal->live != 0 => it->task_pos = &L->cg_list release css_set_lock T exits --signal->live == 0 cgroup_task_dead(T) // css_set_lock release_task(T) cgroup_task_release(T) release_task(L) // zap_leader cgroup_task_release(L) put_task_struct_rcu_user(L) ...RCU... put_task_struct(L) L->usage = 0 /* L still on dying_tasks */ ...RCU... __put_task_struct(L) css_task_iter_next() // another iteration take css_set_lock it->task_pos = &L->cg_list get_task_struct(L) => addition on 0 drop css_set_lock cgroup_task_free(L) css_set_skip_task_iters() // dying skip comes too late free_task(L) cgroup_procs_show() task_pid_vnr(L)•CVE-2026-98163