CVE-2025-21973

Published Apr 1, 2025

Last updated 9 months ago

Overview

Description
In the Linux kernel, the following vulnerability has been resolved: eth: bnxt: fix kernel panic in the bnxt_get_queue_stats{rx | tx} When qstats-get operation is executed, callbacks of netdev_stats_ops are called. The bnxt_get_queue_stats{rx | tx} collect per-queue stats from sw_stats in the rings. But {rx | tx | cp}_ring are allocated when the interface is up. So, these rings are not allocated when the interface is down. The qstats-get is allowed even if the interface is down. However, the bnxt_get_queue_stats{rx | tx}() accesses cp_ring and tx_ring without null check. So, it needs to avoid accessing rings if the interface is down. Reproducer: ip link set $interface down ./cli.py --spec netdev.yaml --dump qstats-get OR ip link set $interface down python ./stats.py Splat looks like: BUG: kernel NULL pointer dereference, address: 0000000000000000 #PF: supervisor read access in kernel mode #PF: error_code(0x0000) - not-present page PGD 1680fa067 P4D 1680fa067 PUD 16be3b067 PMD 0 Oops: Oops: 0000 [#1] PREEMPT SMP NOPTI CPU: 0 UID: 0 PID: 1495 Comm: python3 Not tainted 6.14.0-rc4+ #32 5cd0f999d5a15c574ac72b3e4b907341 Hardware name: ASUS System Product Name/PRIME Z690-P D4, BIOS 0603 11/01/2021 RIP: 0010:bnxt_get_queue_stats_rx+0xf/0x70 [bnxt_en] Code: c6 87 b5 18 00 00 02 eb a2 66 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 0f 1f 44 01 RSP: 0018:ffffabef43cdb7e0 EFLAGS: 00010282 RAX: 0000000000000000 RBX: ffffffffc04c8710 RCX: 0000000000000000 RDX: ffffabef43cdb858 RSI: 0000000000000000 RDI: ffff8d504e850000 RBP: ffff8d506c9f9c00 R08: 0000000000000004 R09: ffff8d506bcd901c R10: 0000000000000015 R11: ffff8d506bcd9000 R12: 0000000000000000 R13: ffffabef43cdb8c0 R14: ffff8d504e850000 R15: 0000000000000000 FS: 00007f2c5462b080(0000) GS:ffff8d575f600000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000000000 CR3: 0000000167fd0000 CR4: 00000000007506f0 PKRU: 55555554 Call Trace: <TASK> ? __die+0x20/0x70 ? page_fault_oops+0x15a/0x460 ? sched_balance_find_src_group+0x58d/0xd10 ? exc_page_fault+0x6e/0x180 ? asm_exc_page_fault+0x22/0x30 ? bnxt_get_queue_stats_rx+0xf/0x70 [bnxt_en cdd546fd48563c280cfd30e9647efa420db07bf1] netdev_nl_stats_by_netdev+0x2b1/0x4e0 ? xas_load+0x9/0xb0 ? xas_find+0x183/0x1d0 ? xa_find+0x8b/0xe0 netdev_nl_qstats_get_dumpit+0xbf/0x1e0 genl_dumpit+0x31/0x90 netlink_dump+0x1a8/0x360
Source
416baaa9-dc9f-4396-8d5f-8c081fb06d67
NVD status
Analyzed
Products
linux_kernel

Risk scores

CVSS 3.1

Type
Primary
Base score
7.1
Impact score
5.2
Exploitability score
1.8
Vector string
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H
Severity
HIGH

Weaknesses

nvd@nist.gov
NVD-CWE-noinfo

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