CVE-2025-38444

Published Jul 25, 2025

Last updated 10 months ago

Overview

Description
In the Linux kernel, the following vulnerability has been resolved: raid10: cleanup memleak at raid10_make_request If raid10_read_request or raid10_write_request registers a new request and the REQ_NOWAIT flag is set, the code does not free the malloc from the mempool. unreferenced object 0xffff8884802c3200 (size 192): comm "fio", pid 9197, jiffies 4298078271 hex dump (first 32 bytes): 00 00 00 00 00 00 00 00 88 41 02 00 00 00 00 00 .........A...... 08 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ backtrace (crc c1a049a2): __kmalloc+0x2bb/0x450 mempool_alloc+0x11b/0x320 raid10_make_request+0x19e/0x650 [raid10] md_handle_request+0x3b3/0x9e0 __submit_bio+0x394/0x560 __submit_bio_noacct+0x145/0x530 submit_bio_noacct_nocheck+0x682/0x830 __blkdev_direct_IO_async+0x4dc/0x6b0 blkdev_read_iter+0x1e5/0x3b0 __io_read+0x230/0x1110 io_read+0x13/0x30 io_issue_sqe+0x134/0x1180 io_submit_sqes+0x48c/0xe90 __do_sys_io_uring_enter+0x574/0x8b0 do_syscall_64+0x5c/0xe0 entry_SYSCALL_64_after_hwframe+0x76/0x7e V4: changing backing tree to see if CKI tests will pass. The patch code has not changed between any versions.
Source
416baaa9-dc9f-4396-8d5f-8c081fb06d67
NVD status
Analyzed
Products
linux_kernel, debian_linux

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