CVE-2026-98851

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

netfilter: nft_flow_offload: drop flowtable reference on init error path

nft_flow_offload_init() bumps the flowtable use count with

nft_use_inc() before calling nf_ct_netns_get(). When the latter

fails, the error is returned as-is and the reference is leaked.

The upper layers do not balance it either: nf_tables_newexpr()

clears expr->ops when the expression init callback fails, so the

nft_expr_more() iteration in nft_rule_expr_deactivate() and

nf_tables_rule_destroy() stops right before the failed expression

and its ->destroy callback, which would drop the reference, never

runs.

Each failed rule addition therefore leaks one flowtable reference

and the flowtable can no longer be removed: NFT_MSG_DELFLOWTABLE

keeps reporting -EBUSY even though no rule references it.

Save the nf_ct_netns_get() return value and undo the nft_use_inc()

when it fails, restoring the inc/dec pairing within

nft_flow_offload_init() itself.