CVE-2022-49741

Published Mar 27, 2025

Last updated a year ago

Overview

Description
In the Linux kernel, the following vulnerability has been resolved: fbdev: smscufx: fix error handling code in ufx_usb_probe The current error handling code in ufx_usb_probe have many unmatching issues, e.g., missing ufx_free_usb_list, destroy_modedb label should only include framebuffer_release, fb_dealloc_cmap only matches fb_alloc_cmap. My local syzkaller reports a memory leak bug: memory leak in ufx_usb_probe BUG: memory leak unreferenced object 0xffff88802f879580 (size 128): comm "kworker/0:7", pid 17416, jiffies 4295067474 (age 46.710s) hex dump (first 32 bytes): 80 21 7c 2e 80 88 ff ff 18 d0 d0 0c 80 88 ff ff .!|............. 00 d0 d0 0c 80 88 ff ff e0 ff ff ff 0f 00 00 00 ................ backtrace: [<ffffffff814c99a0>] kmalloc_trace+0x20/0x90 mm/slab_common.c:1045 [<ffffffff824d219c>] kmalloc include/linux/slab.h:553 [inline] [<ffffffff824d219c>] kzalloc include/linux/slab.h:689 [inline] [<ffffffff824d219c>] ufx_alloc_urb_list drivers/video/fbdev/smscufx.c:1873 [inline] [<ffffffff824d219c>] ufx_usb_probe+0x11c/0x15a0 drivers/video/fbdev/smscufx.c:1655 [<ffffffff82d17927>] usb_probe_interface+0x177/0x370 drivers/usb/core/driver.c:396 [<ffffffff82712f0d>] call_driver_probe drivers/base/dd.c:560 [inline] [<ffffffff82712f0d>] really_probe+0x12d/0x390 drivers/base/dd.c:639 [<ffffffff8271322f>] __driver_probe_device+0xbf/0x140 drivers/base/dd.c:778 [<ffffffff827132da>] driver_probe_device+0x2a/0x120 drivers/base/dd.c:808 [<ffffffff82713c27>] __device_attach_driver+0xf7/0x150 drivers/base/dd.c:936 [<ffffffff82710137>] bus_for_each_drv+0xb7/0x100 drivers/base/bus.c:427 [<ffffffff827136b5>] __device_attach+0x105/0x2d0 drivers/base/dd.c:1008 [<ffffffff82711d36>] bus_probe_device+0xc6/0xe0 drivers/base/bus.c:487 [<ffffffff8270e242>] device_add+0x642/0xdc0 drivers/base/core.c:3517 [<ffffffff82d14d5f>] usb_set_configuration+0x8ef/0xb80 drivers/usb/core/message.c:2170 [<ffffffff82d2576c>] usb_generic_driver_probe+0x8c/0xc0 drivers/usb/core/generic.c:238 [<ffffffff82d16ffc>] usb_probe_device+0x5c/0x140 drivers/usb/core/driver.c:293 [<ffffffff82712f0d>] call_driver_probe drivers/base/dd.c:560 [inline] [<ffffffff82712f0d>] really_probe+0x12d/0x390 drivers/base/dd.c:639 [<ffffffff8271322f>] __driver_probe_device+0xbf/0x140 drivers/base/dd.c:778 Fix this bug by rewriting the error handling code in ufx_usb_probe.
Source
416baaa9-dc9f-4396-8d5f-8c081fb06d67
NVD status
Modified
Products
linux_kernel

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-401
134c704f-9b21-4f2e-91b3-4a467353bcc0
CWE-401

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