CVE-2025-38035

Published Jun 18, 2025

Last updated 8 days ago

Overview

Description
In the Linux kernel, the following vulnerability has been resolved: nvmet-tcp: don't restore null sk_state_change queue->state_change is set as part of nvmet_tcp_set_queue_sock(), but if the TCP connection isn't established when nvmet_tcp_set_queue_sock() is called then queue->state_change isn't set and sock->sk->sk_state_change isn't replaced. As such we don't need to restore sock->sk->sk_state_change if queue->state_change is NULL. This avoids NULL pointer dereferences such as this: [ 286.462026][ C0] BUG: kernel NULL pointer dereference, address: 0000000000000000 [ 286.462814][ C0] #PF: supervisor instruction fetch in kernel mode [ 286.463796][ C0] #PF: error_code(0x0010) - not-present page [ 286.464392][ C0] PGD 8000000140620067 P4D 8000000140620067 PUD 114201067 PMD 0 [ 286.465086][ C0] Oops: Oops: 0010 [#1] SMP KASAN PTI [ 286.465559][ C0] CPU: 0 UID: 0 PID: 1628 Comm: nvme Not tainted 6.15.0-rc2+ #11 PREEMPT(voluntary) [ 286.466393][ C0] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.3-3.fc41 04/01/2014 [ 286.467147][ C0] RIP: 0010:0x0 [ 286.467420][ C0] Code: Unable to access opcode bytes at 0xffffffffffffffd6. [ 286.467977][ C0] RSP: 0018:ffff8883ae008580 EFLAGS: 00010246 [ 286.468425][ C0] RAX: 0000000000000000 RBX: ffff88813fd34100 RCX: ffffffffa386cc43 [ 286.469019][ C0] RDX: 1ffff11027fa68b6 RSI: 0000000000000008 RDI: ffff88813fd34100 [ 286.469545][ C0] RBP: ffff88813fd34160 R08: 0000000000000000 R09: ffffed1027fa682c [ 286.470072][ C0] R10: ffff88813fd34167 R11: 0000000000000000 R12: ffff88813fd344c3 [ 286.470585][ C0] R13: ffff88813fd34112 R14: ffff88813fd34aec R15: ffff888132cdd268 [ 286.471070][ C0] FS: 00007fe3c04c7d80(0000) GS:ffff88840743f000(0000) knlGS:0000000000000000 [ 286.471644][ C0] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 286.472543][ C0] CR2: ffffffffffffffd6 CR3: 000000012daca000 CR4: 00000000000006f0 [ 286.473500][ C0] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 286.474467][ C0] DR3: 0000000000000000 DR6: 00000000ffff07f0 DR7: 0000000000000400 [ 286.475453][ C0] Call Trace: [ 286.476102][ C0] <IRQ> [ 286.476719][ C0] tcp_fin+0x2bb/0x440 [ 286.477429][ C0] tcp_data_queue+0x190f/0x4e60 [ 286.478174][ C0] ? __build_skb_around+0x234/0x330 [ 286.478940][ C0] ? rcu_is_watching+0x11/0xb0 [ 286.479659][ C0] ? __pfx_tcp_data_queue+0x10/0x10 [ 286.480431][ C0] ? tcp_try_undo_loss+0x640/0x6c0 [ 286.481196][ C0] ? seqcount_lockdep_reader_access.constprop.0+0x82/0x90 [ 286.482046][ C0] ? kvm_clock_get_cycles+0x14/0x30 [ 286.482769][ C0] ? ktime_get+0x66/0x150 [ 286.483433][ C0] ? rcu_is_watching+0x11/0xb0 [ 286.484146][ C0] tcp_rcv_established+0x6e4/0x2050 [ 286.484857][ C0] ? rcu_is_watching+0x11/0xb0 [ 286.485523][ C0] ? ipv4_dst_check+0x160/0x2b0 [ 286.486203][ C0] ? __pfx_tcp_rcv_established+0x10/0x10 [ 286.486917][ C0] ? lock_release+0x217/0x2c0 [ 286.487595][ C0] tcp_v4_do_rcv+0x4d6/0x9b0 [ 286.488279][ C0] tcp_v4_rcv+0x2af8/0x3e30 [ 286.488904][ C0] ? raw_local_deliver+0x51b/0xad0 [ 286.489551][ C0] ? rcu_is_watching+0x11/0xb0 [ 286.490198][ C0] ? __pfx_tcp_v4_rcv+0x10/0x10 [ 286.490813][ C0] ? __pfx_raw_local_deliver+0x10/0x10 [ 286.491487][ C0] ? __pfx_nf_confirm+0x10/0x10 [nf_conntrack] [ 286.492275][ C0] ? rcu_is_watching+0x11/0xb0 [ 286.492900][ C0] ip_protocol_deliver_rcu+0x8f/0x370 [ 286.493579][ C0] ip_local_deliver_finish+0x297/0x420 [ 286.494268][ C0] ip_local_deliver+0x168/0x430 [ 286.494867][ C0] ? __pfx_ip_local_deliver+0x10/0x10 [ 286.495498][ C0] ? __pfx_ip_local_deliver_finish+0x10/0x10 [ 286.496204][ C0] ? ip_rcv_finish_core+0x19a/0x1f20 [ 286.496806][ C0] ? lock_release+0x217/0x2c0 [ 286.497414][ C0] ip_rcv+0x455/0x6e0 [ 286.497945][ C0] ? __pfx_ip_rcv+0x10/0x10 [ ---truncated---
Source
416baaa9-dc9f-4396-8d5f-8c081fb06d67
NVD status
Modified
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-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