Re: [PATCH v2] netfilter: protect nft_ct_pcpu_template_refcnt with mutex

[Pablo Neira Ayuso]

On Tue, Aug 10, 2021 at 03:59:20PM +0300, Pavel Skripkin wrote:
> Syzbot hit use-after-free in nf_tables_dump_sets. The problem was in
> missing lock protection for nft_ct_pcpu_template_refcnt.
> 
> Before commit f102d66b335a ("netfilter: nf_tables: use dedicated
> mutex to guard transactions") all transactions were serialized by global
> mutex, but then global mutex was changed to local per netnamespace
> commit_mutex.
> 
> This change causes use-after-free bug, when 2 netnamespaces concurently
> changing nft_ct_pcpu_template_refcnt without proper locking. Fix it by
> adding nft_ct_pcpu_mutex and protect all nft_ct_pcpu_template_refcnt
> changes with it.

Applied to nf.git, thanks