Hi Alexei, I love your patch! Perhaps something to improve: [auto build test WARNING on bpf-next/master] url: https://github.com/0day-ci/linux/commits/Alexei-Starovoitov/bpf-Pointers-beyond-packet-end/20201022-022139 base: https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next.git master config: i386-randconfig-r026-20201021 (attached as .config) compiler: gcc-9 (Debian 9.3.0-15) 9.3.0 reproduce (this is a W=1 build): # https://github.com/0day-ci/linux/commit/1aa4c81ae1dbbc3b6de7416f0384cde6cc8739b1 git remote add linux-review https://github.com/0day-ci/linux git fetch --no-tags linux-review Alexei-Starovoitov/bpf-Pointers-beyond-packet-end/20201022-022139 git checkout 1aa4c81ae1dbbc3b6de7416f0384cde6cc8739b1 # save the attached .config to linux build tree make W=1 ARCH=i386 If you fix the issue, kindly add following tag as appropriate Reported-by: kernel test robot All warnings (new ones prefixed by >>): kernel/bpf/verifier.c: In function 'is_pkt_ptr_branch_taken': >> kernel/bpf/verifier.c:7029:24: warning: variable 'pkt_end' set but not used [-Wunused-but-set-variable] 7029 | struct bpf_reg_state *pkt_end, *pkt; | ^~~~~~~ In file included from include/linux/bpf_verifier.h:8, from kernel/bpf/verifier.c:12: kernel/bpf/verifier.c: In function 'jit_subprogs': include/linux/filter.h:345:4: warning: cast between incompatible function types from 'unsigned int (*)(const void *, const struct bpf_insn *)' to 'u64 (*)(u64, u64, u64, u64, u64)' {aka 'long long unsigned int (*)(long long unsigned int, long long unsigned int, long long unsigned int, long long unsigned int, long long unsigned int)'} [-Wcast-function-type] 345 | ((u64 (*)(u64, u64, u64, u64, u64))(x)) | ^ kernel/bpf/verifier.c:10793:16: note: in expansion of macro 'BPF_CAST_CALL' 10793 | insn->imm = BPF_CAST_CALL(func[subprog]->bpf_func) - | ^~~~~~~~~~~~~ kernel/bpf/verifier.c: In function 'fixup_bpf_calls': include/linux/filter.h:345:4: warning: cast between incompatible function types from 'void * (* const)(struct bpf_map *, void *)' to 'u64 (*)(u64, u64, u64, u64, u64)' {aka 'long long unsigned int (*)(long long unsigned int, long long unsigned int, long long unsigned int, long long unsigned int, long long unsigned int)'} [-Wcast-function-type] 345 | ((u64 (*)(u64, u64, u64, u64, u64))(x)) | ^ kernel/bpf/verifier.c:11186:17: note: in expansion of macro 'BPF_CAST_CALL' 11186 | insn->imm = BPF_CAST_CALL(ops->map_lookup_elem) - | ^~~~~~~~~~~~~ include/linux/filter.h:345:4: warning: cast between incompatible function types from 'int (* const)(struct bpf_map *, void *, void *, u64)' {aka 'int (* const)(struct bpf_map *, void *, void *, long long unsigned int)'} to 'u64 (*)(u64, u64, u64, u64, u64)' {aka 'long long unsigned int (*)(long long unsigned int, long long unsigned int, long long unsigned int, long long unsigned int, long long unsigned int)'} [-Wcast-function-type] 345 | ((u64 (*)(u64, u64, u64, u64, u64))(x)) | ^ kernel/bpf/verifier.c:11190:17: note: in expansion of macro 'BPF_CAST_CALL' 11190 | insn->imm = BPF_CAST_CALL(ops->map_update_elem) - | ^~~~~~~~~~~~~ include/linux/filter.h:345:4: warning: cast between incompatible function types from 'int (* const)(struct bpf_map *, void *)' to 'u64 (*)(u64, u64, u64, u64, u64)' {aka 'long long unsigned int (*)(long long unsigned int, long long unsigned int, long long unsigned int, long long unsigned int, long long unsigned int)'} [-Wcast-function-type] 345 | ((u64 (*)(u64, u64, u64, u64, u64))(x)) | ^ kernel/bpf/verifier.c:11194:17: note: in expansion of macro 'BPF_CAST_CALL' 11194 | insn->imm = BPF_CAST_CALL(ops->map_delete_elem) - | ^~~~~~~~~~~~~ include/linux/filter.h:345:4: warning: cast between incompatible function types from 'int (* const)(struct bpf_map *, void *, u64)' {aka 'int (* const)(struct bpf_map *, void *, long long unsigned int)'} to 'u64 (*)(u64, u64, u64, u64, u64)' {aka 'long long unsigned int (*)(long long unsigned int, long long unsigned int, long long unsigned int, long long unsigned int, long long unsigned int)'} [-Wcast-function-type] 345 | ((u64 (*)(u64, u64, u64, u64, u64))(x)) | ^ kernel/bpf/verifier.c:11198:17: note: in expansion of macro 'BPF_CAST_CALL' 11198 | insn->imm = BPF_CAST_CALL(ops->map_push_elem) - | ^~~~~~~~~~~~~ include/linux/filter.h:345:4: warning: cast between incompatible function types from 'int (* const)(struct bpf_map *, void *)' to 'u64 (*)(u64, u64, u64, u64, u64)' {aka 'long long unsigned int (*)(long long unsigned int, long long unsigned int, long long unsigned int, long long unsigned int, long long unsigned int)'} [-Wcast-function-type] 345 | ((u64 (*)(u64, u64, u64, u64, u64))(x)) | ^ kernel/bpf/verifier.c:11202:17: note: in expansion of macro 'BPF_CAST_CALL' 11202 | insn->imm = BPF_CAST_CALL(ops->map_pop_elem) - | ^~~~~~~~~~~~~ include/linux/filter.h:345:4: warning: cast between incompatible function types from 'int (* const)(struct bpf_map *, void *)' to 'u64 (*)(u64, u64, u64, u64, u64)' {aka 'long long unsigned int (*)(long long unsigned int, long long unsigned int, long long unsigned int, long long unsigned int, long long unsigned int)'} [-Wcast-function-type] 345 | ((u64 (*)(u64, u64, u64, u64, u64))(x)) | ^ kernel/bpf/verifier.c:11206:17: note: in expansion of macro 'BPF_CAST_CALL' 11206 | insn->imm = BPF_CAST_CALL(ops->map_peek_elem) - | ^~~~~~~~~~~~~ vim +/pkt_end +7029 kernel/bpf/verifier.c 7024 7025 static int is_pkt_ptr_branch_taken(struct bpf_reg_state *dst_reg, 7026 struct bpf_reg_state *src_reg, 7027 u8 opcode) 7028 { > 7029 struct bpf_reg_state *pkt_end, *pkt; 7030 7031 if (src_reg->type == PTR_TO_PACKET_END) { 7032 pkt_end = src_reg; 7033 pkt = dst_reg; 7034 } else if (dst_reg->type == PTR_TO_PACKET_END) { 7035 pkt_end = dst_reg; 7036 pkt = src_reg; 7037 opcode = flip_opcode(opcode); 7038 } else { 7039 return -1; 7040 } 7041 7042 if (pkt->range >= 0) 7043 return -1; 7044 7045 switch (opcode) { 7046 case BPF_JLE: 7047 /* pkt <= pkt_end */ 7048 fallthrough; 7049 case BPF_JGT: 7050 /* pkt > pkt_end */ 7051 if (pkt->range == BEYOND_PKT_END) 7052 /* pkt has at last one extra byte beyond pkt_end */ 7053 return opcode == BPF_JGT; 7054 break; 7055 case BPF_JLT: 7056 /* pkt < pkt_end */ 7057 fallthrough; 7058 case BPF_JGE: 7059 /* pkt >= pkt_end */ 7060 if (pkt->range == BEYOND_PKT_END || pkt->range == AT_PKT_END) 7061 return opcode == BPF_JGE; 7062 break; 7063 } 7064 return -1; 7065 } 7066 --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org