Giuseppe Scrivano <gscrivan@xxxxxxxxxx> wrote:
> SELinux, if enabled, registers for each new network namespace 6
> netfilter hooks. Avoid to use synchronize_net for each new hook, but do
> it once after all the hooks are added. The net benefit on an SMP
> machine with two cores is that creating a new network namespace takes
> -40% of the original time.
>
> Signed-off-by: Giuseppe Scrivano <gscrivan@xxxxxxxxxx>
> ---
> net/netfilter/core.c | 15 ++++++++++++---
> 1 file changed, 12 insertions(+), 3 deletions(-)
>
> diff --git a/net/netfilter/core.c b/net/netfilter/core.c
> index 52cd2901a097..beeb0b36f429 100644
> --- a/net/netfilter/core.c
> +++ b/net/netfilter/core.c
> @@ -252,7 +252,7 @@ static struct nf_hook_entries __rcu **nf_hook_entry_head(struct net *net, const
> return NULL;
> }
>
> -int nf_register_net_hook(struct net *net, const struct nf_hook_ops *reg)
> +static int __nf_register_net_hook(struct net *net, const struct nf_hook_ops *reg)
> {
> struct nf_hook_entries *p, *new_hooks;
> struct nf_hook_entries __rcu **pp;
> @@ -291,11 +291,19 @@ int nf_register_net_hook(struct net *net, const struct nf_hook_ops *reg)
> #ifdef HAVE_JUMP_LABEL
> static_key_slow_inc(&nf_hooks_needed[reg->pf][reg->hooknum]);
> #endif
> - synchronize_net();
> BUG_ON(p == new_hooks);
> kvfree(p);
This adds use after free?
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