Re: [PATCH] net/ipv4/ip_fragment:fix missing Flags reserved bit set in iphdr

Hi meijusan,

url:    https://github.com/0day-ci/linux/commits/meijusan/net-ipv4-ip_fragment-fix-missing-Flags-reserved-bit-set-in-iphdr/20210505-212826
base:   https://git.kernel.org/pub/scm/linux/kernel/git/horms/ipvs.git master
config: i386-randconfig-m021-20210505 (attached as .config)
compiler: gcc-9 (Debian 9.3.0-22) 9.3.0

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <redacted>
Reported-by: Dan Carpenter <redacted>

smatch warnings:
net/ipv4/ip_output.c:655 ip_fraglist_prepare() error: uninitialized symbol 'ip_evil'.

vim +/ip_evil +655 net/ipv4/ip_output.c

c8b17be0b7a45d Pablo Neira Ayuso 2019-05-29  631  void ip_fraglist_prepare(struct sk_buff *skb, struct ip_fraglist_iter *iter)
c8b17be0b7a45d Pablo Neira Ayuso 2019-05-29  632  {
c8b17be0b7a45d Pablo Neira Ayuso 2019-05-29  633  	unsigned int hlen = iter->hlen;
c8b17be0b7a45d Pablo Neira Ayuso 2019-05-29  634  	struct iphdr *iph = iter->iph;
c8b17be0b7a45d Pablo Neira Ayuso 2019-05-29  635  	struct sk_buff *frag;
c6cde148fcd3bf meijusan          2021-05-05  636  	bool ip_evil;
c8b17be0b7a45d Pablo Neira Ayuso 2019-05-29  637  
c8b17be0b7a45d Pablo Neira Ayuso 2019-05-29  638  	frag = iter->frag;
c8b17be0b7a45d Pablo Neira Ayuso 2019-05-29  639  	frag->ip_summed = CHECKSUM_NONE;
c8b17be0b7a45d Pablo Neira Ayuso 2019-05-29  640  	skb_reset_transport_header(frag);
c8b17be0b7a45d Pablo Neira Ayuso 2019-05-29  641  	__skb_push(frag, hlen);
c8b17be0b7a45d Pablo Neira Ayuso 2019-05-29  642  	skb_reset_network_header(frag);
c8b17be0b7a45d Pablo Neira Ayuso 2019-05-29  643  	memcpy(skb_network_header(frag), iph, hlen);
c6cde148fcd3bf meijusan          2021-05-05  644  	if (ntohs(iph->frag_off) & IP_EVIL)
c6cde148fcd3bf meijusan          2021-05-05  645  		ip_evil = true;

"ip_evil" is never set to false.

c8b17be0b7a45d Pablo Neira Ayuso 2019-05-29  646  	iter->iph = ip_hdr(frag);
c8b17be0b7a45d Pablo Neira Ayuso 2019-05-29  647  	iph = iter->iph;
c8b17be0b7a45d Pablo Neira Ayuso 2019-05-29  648  	iph->tot_len = htons(frag->len);
c8b17be0b7a45d Pablo Neira Ayuso 2019-05-29  649  	ip_copy_metadata(frag, skb);
c8b17be0b7a45d Pablo Neira Ayuso 2019-05-29  650  	iter->offset += skb->len - hlen;
c8b17be0b7a45d Pablo Neira Ayuso 2019-05-29  651  	iph->frag_off = htons(iter->offset >> 3);
c8b17be0b7a45d Pablo Neira Ayuso 2019-05-29  652  	if (frag->next)
c8b17be0b7a45d Pablo Neira Ayuso 2019-05-29  653  		iph->frag_off |= htons(IP_MF);
c6cde148fcd3bf meijusan          2021-05-05  654  
c6cde148fcd3bf meijusan          2021-05-05 @655  	if (ip_evil)
c6cde148fcd3bf meijusan          2021-05-05  656  		iph->frag_off |= htons(IP_EVIL);
c6cde148fcd3bf meijusan          2021-05-05  657  
c8b17be0b7a45d Pablo Neira Ayuso 2019-05-29  658  	/* Ready, complete checksum */
c8b17be0b7a45d Pablo Neira Ayuso 2019-05-29  659  	ip_send_check(iph);
c8b17be0b7a45d Pablo Neira Ayuso 2019-05-29  660  }

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org