Re: [PATCH] netfilter: nft_socket: socket expressions for GID & UID

[Florian Westphal <fw@strlen.de>]

Topi Miettinen <toiwoton@gmail.com> wrote:
> On 26.4.2022 1.34, Florian Westphal wrote:
> > Topi Miettinen <toiwoton@gmail.com> wrote:
> > > On 20.4.2022 21.54, Topi Miettinen wrote:
> > > > Add socket expressions for checking GID or UID of the originating
> > > > socket. These work also on input side, unlike meta skuid/skgid.
> > > 
> > > Unfortunately, there's a reproducible kernel BUG when closing a local
> > > connection:
> > > 
> > > Apr 25 21:18:13 kernel:
> > > ==================================================================
> > > Apr 25 21:18:13 kernel: BUG: KASAN: null-ptr-deref in
> > > nf_sk_lookup_slow_v6+0x45b/0x590 [nf_socket_ipv6]
> > 
> > You can pass this to scripts/faddr2line to get the location of the null deref.
> 
> Didn't work,

?

You pass the object file and the nf_sk_lookup_slow_v6+0x45b/0x590 info.
I can't do it for you because I lack the object file and the exact
source code.

> net/ipv6/netfilter/nf_socket_ipv6.c:
> 
> static struct sock *
> nf_socket_get_sock_v6(struct net *net, struct sk_buff *skb, int doff,
>                       const u8 protocol,
>                       const struct in6_addr *saddr, const struct in6_addr
> *daddr,
>                       const __be16 sport, const __be16 dport,
>                       const struct net_device *in)
> {
>         switch (protocol) {
>         case IPPROTO_TCP:
>                 return inet6_lookup(net, &tcp_hashinfo, skb, doff,
>                                     saddr, sport, daddr, dport,
>                                     in->ifindex);

What does that rule look like?  Seems like no input interface is
available, seems like a bug in existing code?