CVE-2025-71125

Published Jan 14, 2026

Last updated 5 days ago

Overview

Description
In the Linux kernel, the following vulnerability has been resolved: tracing: Do not register unsupported perf events Synthetic events currently do not have a function to register perf events. This leads to calling the tracepoint register functions with a NULL function pointer which triggers: ------------[ cut here ]------------ WARNING: kernel/tracepoint.c:175 at tracepoint_add_func+0x357/0x370, CPU#2: perf/2272 Modules linked in: kvm_intel kvm irqbypass CPU: 2 UID: 0 PID: 2272 Comm: perf Not tainted 6.18.0-ftest-11964-ge022764176fc-dirty #323 PREEMPTLAZY Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.17.0-debian-1.17.0-1 04/01/2014 RIP: 0010:tracepoint_add_func+0x357/0x370 Code: 28 9c e8 4c 0b f5 ff eb 0f 4c 89 f7 48 c7 c6 80 4d 28 9c e8 ab 89 f4 ff 31 c0 5b 41 5c 41 5d 41 5e 41 5f 5d c3 cc cc cc cc cc <0f> 0b 49 c7 c6 ea ff ff ff e9 ee fe ff ff 0f 0b e9 f9 fe ff ff 0f RSP: 0018:ffffabc0c44d3c40 EFLAGS: 00010246 RAX: 0000000000000001 RBX: ffff9380aa9e4060 RCX: 0000000000000000 RDX: 000000000000000a RSI: ffffffff9e1d4a98 RDI: ffff937fcf5fd6c8 RBP: 0000000000000001 R08: 0000000000000007 R09: ffff937fcf5fc780 R10: 0000000000000003 R11: ffffffff9c193910 R12: 000000000000000a R13: ffffffff9e1e5888 R14: 0000000000000000 R15: ffffabc0c44d3c78 FS: 00007f6202f5f340(0000) GS:ffff93819f00f000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 000055d3162281a8 CR3: 0000000106a56003 CR4: 0000000000172ef0 Call Trace: <TASK> tracepoint_probe_register+0x5d/0x90 synth_event_reg+0x3c/0x60 perf_trace_event_init+0x204/0x340 perf_trace_init+0x85/0xd0 perf_tp_event_init+0x2e/0x50 perf_try_init_event+0x6f/0x230 ? perf_event_alloc+0x4bb/0xdc0 perf_event_alloc+0x65a/0xdc0 __se_sys_perf_event_open+0x290/0x9f0 do_syscall_64+0x93/0x7b0 ? entry_SYSCALL_64_after_hwframe+0x76/0x7e ? trace_hardirqs_off+0x53/0xc0 entry_SYSCALL_64_after_hwframe+0x76/0x7e Instead, have the code return -ENODEV, which doesn't warn and has perf error out with: # perf record -e synthetic:futex_wait Error: The sys_perf_event_open() syscall returned with 19 (No such device) for event (synthetic:futex_wait). "dmesg | grep -i perf" may provide additional information. Ideally perf should support synthetic events, but for now just fix the warning. The support can come later.
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