Phil Sutter <phil@xxxxxx> wrote:
> +static int nf_tables_dumpreset_set(struct sk_buff *skb,
> + struct netlink_callback *cb)
> +{
> + struct nftables_pernet *nft_net = nft_pernet(sock_net(skb->sk));
> + struct nft_set_dump_ctx *dump_ctx = cb->data;
> + int ret, skip = cb->args[0];
> +
> + mutex_lock(&nft_net->commit_mutex);
> + ret = nf_tables_dump_set(skb, cb);
> + mutex_unlock(&nft_net->commit_mutex);
> +
> + if (cb->args[0] > skip)
> + audit_log_nft_set_reset(dump_ctx->ctx.table, cb->seq,
> + cb->args[0] - skip);
> +
Once commit_mutex is dropped, parallel user can
delete table, and ctx.table references garbage.
So I think this needs to be done under mutex.
> c.data = &dump_ctx;
> @@ -6108,18 +6178,25 @@ static int nf_tables_getsetelem(struct sk_buff *skb,
> if (!nla[NFTA_SET_ELEM_LIST_ELEMENTS])
> return -EINVAL;
>
> + if (!try_module_get(THIS_MODULE))
> + return -EINVAL;
> + rcu_read_unlock();
> + mutex_lock(&nft_net->commit_mutex);
> + rcu_read_lock();
Why do we need to regain the rcu read lock here?
Are we tripping over a now bogus rcu_derefence check or is there
another reason?
