Re: [PATCH net-next] xfrm: Remove unnecessary NULL check in xfrm_lookup_with_ifid()

[Dan Carpenter]

On Wed, Mar 19, 2025 at 06:38:49PM +0100, Paolo Abeni wrote:
> On 3/12/25 6:21 PM, Dan Carpenter wrote:
> > This NULL check is unnecessary and can be removed.  It confuses
> > Smatch static analysis tool because it makes Smatch think that
> > xfrm_lookup_with_ifid() can return a mix of NULL pointers and errors so
> > it creates a lot of false positives.  Remove it.
> > 
> > Signed-off-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
> > ---
> > I have wanted to remove this NULL check for a long time.  Someone
> > said it could be done safely.  But please, please, review this
> > carefully.
> 
> I think it's better if this patch goes first into the ipsec/xfrm tree,
> so that hopefully it gets some serious testing before landing into net-next.
> 
> @Steffen, @Herber: could you please take this in your tree?
> 

Thanks.  The issue for me is that I've had a check which complains that
the caller doesn't check for NULL but I've expanded the check and now
there are 16 new warnings.

regards,
dan carpenter

net/mpls/af_mpls.c:633 inet6_fib_lookup_dev() warn: 'dst' can also be NULL
net/xfrm/xfrm_policy.c:2926 xfrm_policy_queue_process() warn: 'dst' can also be NULL
net/xfrm/xfrm_interface_core.c:463 xfrmi_xmit2() warn: 'dst' can also be NULL
net/core/lwt_bpf.c:242 bpf_lwt_xmit_reroute() warn: 'dst' can also be NULL
net/l2tp/l2tp_ip6.c:673 l2tp_ip6_sendmsg() warn: 'dst' can also be NULL
net/l2tp/l2tp_ip6.c:673 l2tp_ip6_sendmsg() warn: 'dst' can also be NULL
net/dccp/ipv6.c:949 dccp_v6_connect() warn: 'dst' can also be NULL
net/ipv4/ip_vti.c:223 vti_xmit() warn: 'dst' can also be NULL
net/ipv6/syncookies.c:249 cookie_v6_check() warn: 'dst' can also be NULL
net/ipv6/syncookies.c:259 cookie_v6_check() warn: 'dst' can also be NULL
net/ipv6/ip6_udp_tunnel.c:171 udp_tunnel6_dst_lookup() warn: 'dst' can also be NULL
net/ipv6/ip6_tunnel.c:1182 ip6_tnl_xmit() warn: 'dst' can also be NULL
net/ipv6/af_inet6.c:859 inet6_sk_rebuild_header() warn: 'dst' can also be NULL
net/ipv6/ip6_vti.c:489 vti6_xmit() warn: 'dst' can also be NULL
net/ipv6/ila/ila_lwt.c:92 ila_output() warn: 'dst' can also be NULL
net/ipv6/ndisc.c:510 ndisc_send_skb() warn: 'dst' can also be NULL
net/ipv6/inet6_connection_sock.c:109 inet6_csk_route_socket() warn: 'dst' can also be NULL
net/ipv6/tcp_ipv6.c:283 tcp_v6_connect() warn: 'dst' can also be NULL
net/ipv6/netfilter/nf_reject_ipv6.c:316 nf_send_reset6() warn: 'dst' can also be NULL
net/ipv6/raw.c:929 rawv6_sendmsg() warn: 'dst' can also be NULL
net/ipv6/raw.c:929 rawv6_sendmsg() warn: 'dst' can also be NULL
net/ipv6/datagram.c:114 ip6_datagram_dst_update() warn: 'dst' can also be NULL
drivers/net/vrf.c:447 vrf_process_v6_outbound() warn: 'dst' can also be NULL
drivers/net/ethernet/chelsio/inline_crypto/chtls/chtls_cm.c:1156 chtls_recv_sock() warn: 'dst' can also be NULL
drivers/net/ethernet/netronome/nfp/flower/action.c:475 nfp_fl_set_tun() warn: 'dst' can also be NULL
drivers/net/ethernet/netronome/nfp/flower/tunnel_conf.c:826 nfp_tunnel_request_route_v6() warn: 'dst' can also be NULL
drivers/net/ethernet/mellanox/mlx5/core/en/tc_tun.c:464 mlx5e_route_lookup_ipv6_get() warn: 'dst' can also be NULL
drivers/net/ethernet/mellanox/mlx5/core/en/tc_tun.c:466 mlx5e_route_lookup_ipv6_get() warn: 'dst' can also be NULL
drivers/net/wireguard/socket.c:153 send6() warn: 'dst' can also be NULL
drivers/infiniband/core/addr.c:434 addr6_resolve() warn: 'dst' can also be NULL