net/netfilter/nf_conntrack_ovs.c:66:19: sparse: sparse: incorrect type in assignment (different modifiers)

[kernel test robot <lkp@intel.com>]

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
head:   fce2dfa773ced15f27dd27cd0b482a7473cdcf2a
commit: ac46f3f35b6e68fb062ae7cf780d516c0cf4c00a netfilter: nf_conntrack_helper: add refcounting from datapath
date:   6 weeks ago
config: x86_64-randconfig-r134-20260717 (https://download.01.org/0day-ci/archive/20260717/202607171742.63buVftr-lkp@intel.com/config)
compiler: gcc-14 (Debian 14.2.0-19) 14.2.0
sparse: v0.6.5-rc1
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20260717/202607171742.63buVftr-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Fixes: ac46f3f35b6e ("netfilter: nf_conntrack_helper: add refcounting from datapath")
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202607171742.63buVftr-lkp@intel.com/

sparse warnings: (new ones prefixed by >>)
>> net/netfilter/nf_conntrack_ovs.c:66:19: sparse: sparse: incorrect type in assignment (different modifiers) @@     expected int ( *helper_cb )( ... ) @@     got int ( [noderef] * )( ... ) @@
   net/netfilter/nf_conntrack_ovs.c:66:19: sparse:     expected int ( *helper_cb )( ... )
   net/netfilter/nf_conntrack_ovs.c:66:19: sparse:     got int ( [noderef] * )( ... )

vim +66 net/netfilter/nf_conntrack_ovs.c

    10	
    11	/* 'skb' should already be pulled to nh_ofs. */
    12	int nf_ct_helper(struct sk_buff *skb, struct nf_conn *ct,
    13			 enum ip_conntrack_info ctinfo, u16 proto)
    14	{
    15		int (*helper_cb)(struct sk_buff *skb, unsigned int protoff,
    16				 struct nf_conn *ct,
    17				 enum ip_conntrack_info conntrackinfo);
    18		const struct nf_conntrack_helper *helper;
    19		const struct nf_conn_help *help;
    20		unsigned int protoff;
    21		int err;
    22	
    23		if (ctinfo == IP_CT_RELATED_REPLY)
    24			return NF_ACCEPT;
    25	
    26		help = nfct_help(ct);
    27		if (!help)
    28			return NF_ACCEPT;
    29	
    30		helper = rcu_dereference(help->helper);
    31		if (!helper)
    32			return NF_ACCEPT;
    33	
    34		if (helper->tuple.src.l3num != NFPROTO_UNSPEC &&
    35		    helper->tuple.src.l3num != proto)
    36			return NF_ACCEPT;
    37	
    38		switch (proto) {
    39		case NFPROTO_IPV4:
    40			protoff = ip_hdrlen(skb);
    41			proto = ip_hdr(skb)->protocol;
    42			break;
    43		case NFPROTO_IPV6: {
    44			u8 nexthdr = ipv6_hdr(skb)->nexthdr;
    45			__be16 frag_off;
    46			int ofs;
    47	
    48			ofs = ipv6_skip_exthdr(skb, sizeof(struct ipv6hdr), &nexthdr,
    49					       &frag_off);
    50			if (ofs < 0 || (frag_off & htons(~0x7)) != 0) {
    51				pr_debug("proto header not found\n");
    52				return NF_ACCEPT;
    53			}
    54			protoff = ofs;
    55			proto = nexthdr;
    56			break;
    57		}
    58		default:
    59			WARN_ONCE(1, "helper invoked on non-IP family!");
    60			return NF_DROP;
    61		}
    62	
    63		if (helper->tuple.dst.protonum != proto)
    64			return NF_ACCEPT;
    65	
  > 66		helper_cb = rcu_dereference(helper->help);
    67		if (!helper_cb)
    68			return NF_ACCEPT;
    69	
    70		err = helper_cb(skb, protoff, ct, ctinfo);
    71		if (err != NF_ACCEPT)
    72			return err;
    73	
    74		/* Adjust seqs after helper.  This is needed due to some helpers (e.g.,
    75		 * FTP with NAT) adusting the TCP payload size when mangling IP
    76		 * addresses and/or port numbers in the text-based control connection.
    77		 */
    78		if (test_bit(IPS_SEQ_ADJUST_BIT, &ct->status) &&
    79		    !nf_ct_seq_adjust(skb, ct, ctinfo, protoff))
    80			return NF_DROP;
    81		return NF_ACCEPT;
    82	}
    83	EXPORT_SYMBOL_GPL(nf_ct_helper);
    84	

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