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CVE-2022-48976

Description

In the Linux kernel, the following vulnerability has been resolved:netfilter: flowtable_offload: fix using __this_cpu_add in preemptibleflow_offload_queue_work() can be called in workqueue withoutbh disabled, like the call trace showed in my act_ct testing,calling NF_FLOW_TABLE_STAT_INC() there would cause a calltrace: 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/0xdf0This 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 useNF_FLOW_TABLE_STAT_INC_ATOMIC() for all cases inflow_offload_queue_work().

POC

Reference

No PoCs from references.

Github

- https://github.com/ARPSyndicate/cve-scores