CVE-2022-50304

Published Sep 15, 2025

Last updated a year ago

Overview

Description
In the Linux kernel, the following vulnerability has been resolved: mtd: core: fix possible resource leak in init_mtd() I got the error report while inject fault in init_mtd(): sysfs: cannot create duplicate filename '/devices/virtual/bdi/mtd-0' Call Trace: <TASK> dump_stack_lvl+0x67/0x83 sysfs_warn_dup+0x60/0x70 sysfs_create_dir_ns+0x109/0x120 kobject_add_internal+0xce/0x2f0 kobject_add+0x98/0x110 device_add+0x179/0xc00 device_create_groups_vargs+0xf4/0x100 device_create+0x7b/0xb0 bdi_register_va.part.13+0x58/0x2d0 bdi_register+0x9b/0xb0 init_mtd+0x62/0x171 [mtd] do_one_initcall+0x6c/0x3c0 do_init_module+0x58/0x222 load_module+0x268e/0x27d0 __do_sys_finit_module+0xd5/0x140 do_syscall_64+0x37/0x90 entry_SYSCALL_64_after_hwframe+0x63/0xcd </TASK> kobject_add_internal failed for mtd-0 with -EEXIST, don't try to register things with the same name in the same directory. Error registering mtd class or bdi: -17 If init_mtdchar() fails in init_mtd(), mtd_bdi will not be unregistered, as a result, we can't load the mtd module again, to fix this by calling bdi_unregister(mtd_bdi) after out_procfs label.
Source
416baaa9-dc9f-4396-8d5f-8c081fb06d67
NVD status
Analyzed
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

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