CVE-2025-23130

Published Apr 16, 2025

Last updated a year ago

Overview

Description
In the Linux kernel, the following vulnerability has been resolved: f2fs: fix to avoid panic once fallocation fails for pinfile syzbot reports a f2fs bug as below: ------------[ cut here ]------------ kernel BUG at fs/f2fs/segment.c:2746! CPU: 0 UID: 0 PID: 5323 Comm: syz.0.0 Not tainted 6.13.0-rc2-syzkaller-00018-g7cb1b4663150 #0 RIP: 0010:get_new_segment fs/f2fs/segment.c:2746 [inline] RIP: 0010:new_curseg+0x1f52/0x1f70 fs/f2fs/segment.c:2876 Call Trace: <TASK> __allocate_new_segment+0x1ce/0x940 fs/f2fs/segment.c:3210 f2fs_allocate_new_section fs/f2fs/segment.c:3224 [inline] f2fs_allocate_pinning_section+0xfa/0x4e0 fs/f2fs/segment.c:3238 f2fs_expand_inode_data+0x696/0xca0 fs/f2fs/file.c:1830 f2fs_fallocate+0x537/0xa10 fs/f2fs/file.c:1940 vfs_fallocate+0x569/0x6e0 fs/open.c:327 do_vfs_ioctl+0x258c/0x2e40 fs/ioctl.c:885 __do_sys_ioctl fs/ioctl.c:904 [inline] __se_sys_ioctl+0x80/0x170 fs/ioctl.c:892 do_syscall_x64 arch/x86/entry/common.c:52 [inline] do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83 entry_SYSCALL_64_after_hwframe+0x77/0x7f Concurrent pinfile allocation may run out of free section, result in panic in get_new_segment(), let's expand pin_sem lock coverage to include f2fs_gc(), so that we can make sure to reclaim enough free space for following allocation. In addition, do below changes to enhance error path handling: - call f2fs_bug_on() only in non-pinfile allocation path in get_new_segment(). - call reset_curseg_fields() to reset all fields of curseg in new_curseg()
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
NVD-CWE-noinfo

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