CVE-2022-49703

Published Feb 26, 2025

Last updated a year ago

Overview

Description
In the Linux kernel, the following vulnerability has been resolved: scsi: ibmvfc: Store vhost pointer during subcrq allocation Currently the back pointer from a queue to the vhost adapter isn't set until after subcrq interrupt registration. The value is available when a queue is first allocated and can/should be also set for primary and async queues as well as subcrqs. This fixes a crash observed during kexec/kdump on Power 9 with legacy XICS interrupt controller where a pending subcrq interrupt from the previous kernel can be replayed immediately upon IRQ registration resulting in dereference of a garbage backpointer in ibmvfc_interrupt_scsi(). Kernel attempted to read user page (58) - exploit attempt? (uid: 0) BUG: Kernel NULL pointer dereference on read at 0x00000058 Faulting instruction address: 0xc008000003216a08 Oops: Kernel access of bad area, sig: 11 [#1] ... NIP [c008000003216a08] ibmvfc_interrupt_scsi+0x40/0xb0 [ibmvfc] LR [c0000000082079e8] __handle_irq_event_percpu+0x98/0x270 Call Trace: [c000000047fa3d80] [c0000000123e6180] 0xc0000000123e6180 (unreliable) [c000000047fa3df0] [c0000000082079e8] __handle_irq_event_percpu+0x98/0x270 [c000000047fa3ea0] [c000000008207d18] handle_irq_event+0x98/0x188 [c000000047fa3ef0] [c00000000820f564] handle_fasteoi_irq+0xc4/0x310 [c000000047fa3f40] [c000000008205c60] generic_handle_irq+0x50/0x80 [c000000047fa3f60] [c000000008015c40] __do_irq+0x70/0x1a0 [c000000047fa3f90] [c000000008016d7c] __do_IRQ+0x9c/0x130 [c000000014622f60] [0000000020000000] 0x20000000 [c000000014622ff0] [c000000008016e50] do_IRQ+0x40/0xa0 [c000000014623020] [c000000008017044] replay_soft_interrupts+0x194/0x2f0 [c000000014623210] [c0000000080172a8] arch_local_irq_restore+0x108/0x170 [c000000014623240] [c000000008eb1008] _raw_spin_unlock_irqrestore+0x58/0xb0 [c000000014623270] [c00000000820b12c] __setup_irq+0x49c/0x9f0 [c000000014623310] [c00000000820b7c0] request_threaded_irq+0x140/0x230 [c000000014623380] [c008000003212a50] ibmvfc_register_scsi_channel+0x1e8/0x2f0 [ibmvfc] [c000000014623450] [c008000003213d1c] ibmvfc_init_sub_crqs+0xc4/0x1f0 [ibmvfc] [c0000000146234d0] [c0080000032145a8] ibmvfc_reset_crq+0x150/0x210 [ibmvfc] [c000000014623550] [c0080000032147c8] ibmvfc_init_crq+0x160/0x280 [ibmvfc] [c0000000146235f0] [c00800000321a9cc] ibmvfc_probe+0x2a4/0x530 [ibmvfc]
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