netfilter: flowtable: generalize pending status bit

Overview

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

netfilter: flowtable: generalize pending status bit

Rename NF_FLOW_HW_PENDING to NF_FLOW_PENDING and use it to inhibit the flowtable GC worker until pending hw offload work has been completed.

Apparently, nf_flow_offload_stats() can schedule work to retrieve stats while the flow is being removed by GC.

And this bit can also be used in a follow up patch to disable GC until the flow has been fully added in both directions.

Revert the reordering done in commit d644b23afe1e ("netfilter: flowtable: publish HW_DEAD after worker is done") to prevent a race between GC and hw offload handler.

Affected

• Linux >= 2c8897953f3b2ff5498f3f275708a742bfcdbc24 < 4d52b72f3aa68ad0536444e36530bda75070194c
• Linux >= 2c8897953f3b2ff5498f3f275708a742bfcdbc24 < 4033e1a9262c57dfbfc594a591a50fcba63c531a
• Linux >= 2c8897953f3b2ff5498f3f275708a742bfcdbc24 < a2cac45848d1cf31ed190db30f90ba8211e9a8ca
• Linux >= 2c8897953f3b2ff5498f3f275708a742bfcdbc24 < 7c549fb7eecd01fdba7c0d12c01da876ef8a3214
• Linux 5.7

Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.