CVE-2022-48976 Information

Description

In the Linux kernel the following vulnerability has been resolved:

netfilter: flowtable_offload: fix using __this_cpu_add in preemptible

flow_offload_queue_work() can be called in workqueue without bh disabled like the call trace showed in my act_ct testing calling NF_FLOW_TABLE_STAT_INC() there would cause a call trace:

BUG: using __this_cpu_add() in preemptible [00000000] code: kworker/u4:0/138560 caller is flow_offload_queue_work+0xec/0x1b0 [nf_flow_table] Workqueue: act_ct_workqueue tcf_ct_flow_table_cleanup_work [act_ct] Call Trace: dump_stack_lvl+0x33/0x46 check_preemption_disabled+0xc3/0xf0 flow_offload_queue_work+0xec/0x1b0 [nf_flow_table] nf_flow_table_iterate+0x138/0x170 [nf_flow_table] nf_flow_table_free+0x140/0x1a0 [nf_flow_table] tcf_ct_flow_table_cleanup_work+0x2f/0x2b0 [act_ct] process_one_work+0x6a3/0x1030 worker_thread+0x8a/0xdf0

This patch fixes it by using NF_FLOW_TABLE_STAT_INC_ATOMIC() instead in flow_offload_queue_work().

Note that for FLOW_CLS_REPLACE branch in flow_offload_queue_work() it may not be called in preemptible path but it’s good to use NF_FLOW_TABLE_STAT_INC_ATOMIC() for all cases in flow_offload_queue_work().

CVSS Vector

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Reference

https://git.kernel.org/stable/c/a220a11fda012fba506b35929672374c2723ae6d https://git.kernel.org/stable/c/a81047154e7ce4eb8769d5d21adcbc9693542a79

Attack Complexity

LOW

Privileges Required

LOW

User Interaction Required

LOW

Scope

NONE

Confidentiality Impact

UNCHANGED

Integrity Impact

NONE

Availability Impact

NONE

Base Score

HIGH

Base Severity

5.5