Hi Pablo, I love your patch! Yet something to improve: [auto build test ERROR on nf/master] url: https://github.com/0day-ci/linux/commits/Pablo-Neira-Ayuso/netfilter-nft_... base: https://git.kernel.org/pub/scm/linux/kernel/git/pablo/nf.git master config: arm-randconfig-r001-20210615 (attached as .config) compiler: clang version 13.0.0 (https://github.com/llvm/llvm-project 64720f57bea6a6bf033feef4a5751ab9c0c3b401) reproduce (this is a W=1 build): wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross chmod +x ~/bin/make.cross # install arm cross compiling tool for clang build # apt-get install binutils-arm-linux-gnueabi # https://github.com/0day-ci/linux/commit/f572a05becf9cc86053b01e0f0f898334... git remote add linux-review https://github.com/0day-ci/linux git fetch --no-tags linux-review Pablo-Neira-Ayuso/netfilter-nft_exthdr-check-for-IPv6-packet-before-further-processing/20210616-144640 git checkout f572a05becf9cc86053b01e0f0f898334583692a # save the attached .config to linux build tree COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross ARCH=arm If you fix the issue, kindly add following tag as appropriate Reported-by: kernel test robot <lkp(a)intel.com&gt; All errors (new ones prefixed by >>): break; ^ 1 error generated. vim +/break +33 net/netfilter/nft_osf.c 19 20 static void nft_osf_eval(const struct nft_expr *expr, struct nft_regs *regs, 21 const struct nft_pktinfo *pkt) 22 { 23 struct nft_osf *priv = nft_expr_priv(expr); 24 u32 *dest = &regs->data[priv->dreg]; 25 struct sk_buff *skb = pkt->skb; 26 char os_match[NFT_OSF_MAXGENRELEN + 1]; 27 const struct tcphdr *tcp; 28 struct nf_osf_data data; 29 struct tcphdr _tcph; 30 31 if (pkt->tprot != IPPROTO_TCP) { 32 regs->verdict.code = NFT_BREAK; 34 } 35 36 tcp = skb_header_pointer(skb, ip_hdrlen(skb), 37 sizeof(struct tcphdr), &_tcph); 38 if (!tcp) { 39 regs->verdict.code = NFT_BREAK; 40 return; 41 } 42 if (!tcp->syn) { 43 regs->verdict.code = NFT_BREAK; 44 return; 45 } 46 47 if (!nf_osf_find(skb, nf_osf_fingers, priv->ttl, &data)) { 48 strncpy((char *)dest, "unknown", NFT_OSF_MAXGENRELEN); 49 } else { 50 if (priv->flags & NFT_OSF_F_VERSION) 51 snprintf(os_match, NFT_OSF_MAXGENRELEN, "%s:%s", 52 data.genre, data.version); 53 else 54 strlcpy(os_match, data.genre, NFT_OSF_MAXGENRELEN); 55 56 strncpy((char *)dest, os_match, NFT_OSF_MAXGENRELEN); 57 } 58 } 59 --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org