CVE-2022-48976

In the Linux kernel, the following vulnerability has been resolved:

netfilter: flowtableoffload: fix using _thiscpuadd in preemptible

flowoffloadqueuework() can be called in workqueue without bh disabled, like the call trace showed in my actct testing, calling NFFLOWTABLESTATINC() there would cause a call trace:

BUG: using _thiscpuadd() in preemptible [00000000] code: kworker/u4:0/138560 caller is flowoffloadqueuework+0xec/0x1b0 [nfflowtable] Workqueue: actctworkqueue tcfctflowtablecleanupwork [actct] Call Trace: <TASK> dumpstacklvl+0x33/0x46 checkpreemptiondisabled+0xc3/0xf0 flowoffloadqueuework+0xec/0x1b0 [nfflowtable] nfflowtableiterate+0x138/0x170 [nfflowtable] nfflowtablefree+0x140/0x1a0 [nfflowtable] tcfctflowtablecleanupwork+0x2f/0x2b0 [actct] processonework+0x6a3/0x1030 workerthread+0x8a/0xdf0

This patch fixes it by using NFFLOWTABLESTATINCATOMIC() instead in flowoffloadqueuework().

Note that for FLOWCLSREPLACE branch in flowoffloadqueuework(), it may not be called in preemptible path, but it's good to use NFFLOWTABLESTATINCATOMIC() for all cases in flowoffloadqueue_work().