CVE-2025-21953

Published Apr 1, 2025

Last updated a year ago

Overview

Description
In the Linux kernel, the following vulnerability has been resolved: net: mana: cleanup mana struct after debugfs_remove() When on a MANA VM hibernation is triggered, as part of hibernate_snapshot(), mana_gd_suspend() and mana_gd_resume() are called. If during this mana_gd_resume(), a failure occurs with HWC creation, mana_port_debugfs pointer does not get reinitialized and ends up pointing to older, cleaned-up dentry. Further in the hibernation path, as part of power_down(), mana_gd_shutdown() is triggered. This call, unaware of the failures in resume, tries to cleanup the already cleaned up mana_port_debugfs value and hits the following bug: [ 191.359296] mana 7870:00:00.0: Shutdown was called [ 191.359918] BUG: kernel NULL pointer dereference, address: 0000000000000098 [ 191.360584] #PF: supervisor write access in kernel mode [ 191.361125] #PF: error_code(0x0002) - not-present page [ 191.361727] PGD 1080ea067 P4D 0 [ 191.362172] Oops: Oops: 0002 [#1] SMP NOPTI [ 191.362606] CPU: 11 UID: 0 PID: 1674 Comm: bash Not tainted 6.14.0-rc5+ #2 [ 191.363292] Hardware name: Microsoft Corporation Virtual Machine/Virtual Machine, BIOS Hyper-V UEFI Release v4.1 11/21/2024 [ 191.364124] RIP: 0010:down_write+0x19/0x50 [ 191.364537] Code: 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 0f 1f 44 00 00 55 48 89 e5 53 48 89 fb e8 de cd ff ff 31 c0 ba 01 00 00 00 <f0> 48 0f b1 13 75 16 65 48 8b 05 88 24 4c 6a 48 89 43 08 48 8b 5d [ 191.365867] RSP: 0000:ff45fbe0c1c037b8 EFLAGS: 00010246 [ 191.366350] RAX: 0000000000000000 RBX: 0000000000000098 RCX: ffffff8100000000 [ 191.366951] RDX: 0000000000000001 RSI: 0000000000000064 RDI: 0000000000000098 [ 191.367600] RBP: ff45fbe0c1c037c0 R08: 0000000000000000 R09: 0000000000000001 [ 191.368225] R10: ff45fbe0d2b01000 R11: 0000000000000008 R12: 0000000000000000 [ 191.368874] R13: 000000000000000b R14: ff43dc27509d67c0 R15: 0000000000000020 [ 191.369549] FS: 00007dbc5001e740(0000) GS:ff43dc663f380000(0000) knlGS:0000000000000000 [ 191.370213] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 191.370830] CR2: 0000000000000098 CR3: 0000000168e8e002 CR4: 0000000000b73ef0 [ 191.371557] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 191.372192] DR3: 0000000000000000 DR6: 00000000fffe07f0 DR7: 0000000000000400 [ 191.372906] Call Trace: [ 191.373262] <TASK> [ 191.373621] ? show_regs+0x64/0x70 [ 191.374040] ? __die+0x24/0x70 [ 191.374468] ? page_fault_oops+0x290/0x5b0 [ 191.374875] ? do_user_addr_fault+0x448/0x800 [ 191.375357] ? exc_page_fault+0x7a/0x160 [ 191.375971] ? asm_exc_page_fault+0x27/0x30 [ 191.376416] ? down_write+0x19/0x50 [ 191.376832] ? down_write+0x12/0x50 [ 191.377232] simple_recursive_removal+0x4a/0x2a0 [ 191.377679] ? __pfx_remove_one+0x10/0x10 [ 191.378088] debugfs_remove+0x44/0x70 [ 191.378530] mana_detach+0x17c/0x4f0 [ 191.378950] ? __flush_work+0x1e2/0x3b0 [ 191.379362] ? __cond_resched+0x1a/0x50 [ 191.379787] mana_remove+0xf2/0x1a0 [ 191.380193] mana_gd_shutdown+0x3b/0x70 [ 191.380642] pci_device_shutdown+0x3a/0x80 [ 191.381063] device_shutdown+0x13e/0x230 [ 191.381480] kernel_power_off+0x35/0x80 [ 191.381890] hibernate+0x3c6/0x470 [ 191.382312] state_store+0xcb/0xd0 [ 191.382734] kobj_attr_store+0x12/0x30 [ 191.383211] sysfs_kf_write+0x3e/0x50 [ 191.383640] kernfs_fop_write_iter+0x140/0x1d0 [ 191.384106] vfs_write+0x271/0x440 [ 191.384521] ksys_write+0x72/0xf0 [ 191.384924] __x64_sys_write+0x19/0x20 [ 191.385313] x64_sys_call+0x2b0/0x20b0 [ 191.385736] do_syscall_64+0x79/0x150 [ 191.386146] ? __mod_memcg_lruvec_state+0xe7/0x240 [ 191.386676] ? __lruvec_stat_mod_folio+0x79/0xb0 [ 191.387124] ? __pfx_lru_add+0x10/0x10 [ 191.387515] ? queued_spin_unlock+0x9/0x10 [ 191.387937] ? do_anonymous_page+0x33c/0xa00 [ 191.388374] ? __handle_mm_fault+0xcf3/0x1210 [ 191.388805] ? __count_memcg_events+0xbe/0x180 [ 191.389235] ? handle_mm_fault+0xae/0x300 [ 19 ---truncated---
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-476
134c704f-9b21-4f2e-91b3-4a467353bcc0
CWE-476

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