Florent Revest <revest@xxxxxxxxxxxx> wrote: > If nf_conntrack_init_start() fails (for example due to a > register_nf_conntrack_bpf() failure), the nf_conntrack_helper_fini() > clean-up path frees the nf_ct_helper_hash map. > > When built with NF_CONNTRACK=y, further netfilter modules (e.g: > netfilter_conntrack_ftp) can still be loaded and call > nf_conntrack_helpers_register(), independently of whether nf_conntrack > initialized correctly. This accesses the nf_ct_helper_hash dangling > pointer and causes a uaf, possibly leading to random memory corruption. > > This patch guards nf_conntrack_helper_register() from accessing a freed > or uninitialized nf_ct_helper_hash pointer and fixes possible > uses-after-free when loading a conntrack module. Reviewed-by: Florian Westphal <fw@xxxxxxxxx>
