Re: [PATCH] netfilter: amanda: fix RCU pointer typing for nf_nat_amanda_hook

[sun jian]

On Tue, Feb 3, 2026 at 9:50 PM Florian Westphal <fw@xxxxxxxxx> wrote:
>
> Sun Jian <sun.jian.kdev@xxxxxxxxx> wrote:

> > 4. Using rcu_dereference_raw() to fetch the hook address, which
> >    satisfies sparse's type checking for function pointers.
>
> This doesn't look right, esp. step 4.  Why not:
>
> diff --git a/include/linux/netfilter/nf_conntrack_amanda.h b/include/linux/netfilter/nf_conntrack_amanda.h
> --- a/include/linux/netfilter/nf_conntrack_amanda.h
> +++ b/include/linux/netfilter/nf_conntrack_amanda.h
> @@ -7,7 +7,7 @@
>  #include <linux/skbuff.h>
>  #include <net/netfilter/nf_conntrack_expect.h>
>
> -extern unsigned int (*nf_nat_amanda_hook)(struct sk_buff *skb,
> +extern unsigned int (__rcu *nf_nat_amanda_hook)(struct sk_buff *skb,
>                                           enum ip_conntrack_info ctinfo,
>                                           unsigned int protoff,
>                                           unsigned int matchoff,
> diff --git a/net/netfilter/nf_conntrack_amanda.c b/net/netfilter/nf_conntrack_amanda.c
> --- a/net/netfilter/nf_conntrack_amanda.c
> +++ b/net/netfilter/nf_conntrack_amanda.c
> @@ -37,7 +37,7 @@ MODULE_PARM_DESC(master_timeout, "timeout for the master connection");
>  module_param(ts_algo, charp, 0400);
>  MODULE_PARM_DESC(ts_algo, "textsearch algorithm to use (default kmp)");
>
> -unsigned int (*nf_nat_amanda_hook)(struct sk_buff *skb,
> +unsigned int (__rcu *nf_nat_amanda_hook)(struct sk_buff *skb,
>                                    enum ip_conntrack_info ctinfo,
>                                    unsigned int protoff,
>                                    unsigned int matchoff,
> ?
Ack, I'll follow your suggestions and send a V2 shortly.
Thanks for the correction!

Regards,

Sun