Hi Toke,

url:    
https://github.com/0day-ci/linux/commits/Toke-H-iland-J-rgensen/bpf-Support-multi-attach-for-freplace-programs/20200715-211145
base:   https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next.git master
config: x86_64-randconfig-m001-20200715 (attached as .config)
compiler: gcc-9 (Debian 9.3.0-14) 9.3.0

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <l...@intel.com>
Reported-by: Dan Carpenter <dan.carpen...@oracle.com>

New smatch warnings:
kernel/bpf/verifier.c:10900 bpf_check_attach_target() error: we previously 
assumed 'tgt_prog' could be null (see line 10772)

Old smatch warnings:
include/linux/bpf_verifier.h:351 bpf_verifier_log_needed() error: we previously 
assumed 'log' could be null (see line 350)

# 
https://github.com/0day-ci/linux/commit/cc8571ec751a3a6065838e0b15105f8be0ced6fe
git remote add linux-review https://github.com/0day-ci/linux
git remote update linux-review
git checkout cc8571ec751a3a6065838e0b15105f8be0ced6fe
vim +/tgt_prog +10900 kernel/bpf/verifier.c

c2d0f6ffe7709e Toke Høiland-Jørgensen 2020-07-15  10734  int 
bpf_check_attach_target(struct bpf_verifier_log *log,
c2d0f6ffe7709e Toke Høiland-Jørgensen 2020-07-15  10735                         
    const struct bpf_prog *prog,
c2d0f6ffe7709e Toke Høiland-Jørgensen 2020-07-15  10736                         
    const struct bpf_prog *tgt_prog,
c2d0f6ffe7709e Toke Høiland-Jørgensen 2020-07-15  10737                         
    u32 btf_id,
c2d0f6ffe7709e Toke Høiland-Jørgensen 2020-07-15  10738                         
    struct btf_func_model *fmodel,
c2d0f6ffe7709e Toke Høiland-Jørgensen 2020-07-15  10739                         
    long *tgt_addr,
c2d0f6ffe7709e Toke Høiland-Jørgensen 2020-07-15  10740                         
    const char **tgt_name,
c2d0f6ffe7709e Toke Høiland-Jørgensen 2020-07-15  10741                         
    const struct btf_type **tgt_type)
38207291604401 Martin KaFai Lau       2019-10-24  10742  {
be8704ff07d237 Alexei Starovoitov     2020-01-20  10743         bool 
prog_extension = prog->type == BPF_PROG_TYPE_EXT;
f1b9509c2fb0ef Alexei Starovoitov     2019-10-30  10744         const char 
prefix[] = "btf_trace_";
5b92a28aae4dd0 Alexei Starovoitov     2019-11-14  10745         int ret = 0, 
subprog = -1, i;
38207291604401 Martin KaFai Lau       2019-10-24  10746         const struct 
btf_type *t;
5b92a28aae4dd0 Alexei Starovoitov     2019-11-14  10747         bool 
conservative = true;
38207291604401 Martin KaFai Lau       2019-10-24  10748         const char 
*tname;
5b92a28aae4dd0 Alexei Starovoitov     2019-11-14  10749         struct btf *btf;
c2d0f6ffe7709e Toke Høiland-Jørgensen 2020-07-15  10750         long addr = 0;
38207291604401 Martin KaFai Lau       2019-10-24  10751  
f1b9509c2fb0ef Alexei Starovoitov     2019-10-30  10752         if (!btf_id) {
e33243ff1dd2cb Toke Høiland-Jørgensen 2020-07-15  10753                 
bpf_log(log, "Tracing programs must provide btf_id\n");
f1b9509c2fb0ef Alexei Starovoitov     2019-10-30  10754                 return 
-EINVAL;
f1b9509c2fb0ef Alexei Starovoitov     2019-10-30  10755         }
5b92a28aae4dd0 Alexei Starovoitov     2019-11-14  10756         btf = 
bpf_prog_get_target_btf(prog);
5b92a28aae4dd0 Alexei Starovoitov     2019-11-14  10757         if (!btf) {
e33243ff1dd2cb Toke Høiland-Jørgensen 2020-07-15  10758                 
bpf_log(log,
5b92a28aae4dd0 Alexei Starovoitov     2019-11-14  10759                         
"FENTRY/FEXIT program can only be attached to another program annotated with 
BTF\n");
5b92a28aae4dd0 Alexei Starovoitov     2019-11-14  10760                 return 
-EINVAL;
5b92a28aae4dd0 Alexei Starovoitov     2019-11-14  10761         }
5b92a28aae4dd0 Alexei Starovoitov     2019-11-14  10762         t = 
btf_type_by_id(btf, btf_id);
38207291604401 Martin KaFai Lau       2019-10-24  10763         if (!t) {
e33243ff1dd2cb Toke Høiland-Jørgensen 2020-07-15  10764                 
bpf_log(log, "attach_btf_id %u is invalid\n", btf_id);
38207291604401 Martin KaFai Lau       2019-10-24  10765                 return 
-EINVAL;
38207291604401 Martin KaFai Lau       2019-10-24  10766         }
5b92a28aae4dd0 Alexei Starovoitov     2019-11-14  10767         tname = 
btf_name_by_offset(btf, t->name_off);
f1b9509c2fb0ef Alexei Starovoitov     2019-10-30  10768         if (!tname) {
e33243ff1dd2cb Toke Høiland-Jørgensen 2020-07-15  10769                 
bpf_log(log, "attach_btf_id %u doesn't have a name\n", btf_id);
f1b9509c2fb0ef Alexei Starovoitov     2019-10-30  10770                 return 
-EINVAL;
f1b9509c2fb0ef Alexei Starovoitov     2019-10-30  10771         }
5b92a28aae4dd0 Alexei Starovoitov     2019-11-14 @10772         if (tgt_prog) {
5b92a28aae4dd0 Alexei Starovoitov     2019-11-14  10773                 struct 
bpf_prog_aux *aux = tgt_prog->aux;
5b92a28aae4dd0 Alexei Starovoitov     2019-11-14  10774  
5b92a28aae4dd0 Alexei Starovoitov     2019-11-14  10775                 for (i 
= 0; i < aux->func_info_cnt; i++)
5b92a28aae4dd0 Alexei Starovoitov     2019-11-14  10776                         
if (aux->func_info[i].type_id == btf_id) {
5b92a28aae4dd0 Alexei Starovoitov     2019-11-14  10777                         
        subprog = i;
5b92a28aae4dd0 Alexei Starovoitov     2019-11-14  10778                         
        break;
5b92a28aae4dd0 Alexei Starovoitov     2019-11-14  10779                         
}
5b92a28aae4dd0 Alexei Starovoitov     2019-11-14  10780                 if 
(subprog == -1) {
e33243ff1dd2cb Toke Høiland-Jørgensen 2020-07-15  10781                         
bpf_log(log, "Subprog %s doesn't exist\n", tname);
5b92a28aae4dd0 Alexei Starovoitov     2019-11-14  10782                         
return -EINVAL;
5b92a28aae4dd0 Alexei Starovoitov     2019-11-14  10783                 }
5b92a28aae4dd0 Alexei Starovoitov     2019-11-14  10784                 
conservative = aux->func_info_aux[subprog].unreliable;
be8704ff07d237 Alexei Starovoitov     2020-01-20  10785                 if 
(prog_extension) {
be8704ff07d237 Alexei Starovoitov     2020-01-20  10786                         
if (conservative) {
e33243ff1dd2cb Toke Høiland-Jørgensen 2020-07-15  10787                         
        bpf_log(log,
be8704ff07d237 Alexei Starovoitov     2020-01-20  10788                         
                "Cannot replace static functions\n");
be8704ff07d237 Alexei Starovoitov     2020-01-20  10789                         
        return -EINVAL;
be8704ff07d237 Alexei Starovoitov     2020-01-20  10790                         
}
be8704ff07d237 Alexei Starovoitov     2020-01-20  10791                         
if (!prog->jit_requested) {
e33243ff1dd2cb Toke Høiland-Jørgensen 2020-07-15  10792                         
        bpf_log(log,
be8704ff07d237 Alexei Starovoitov     2020-01-20  10793                         
                "Extension programs should be JITed\n");
be8704ff07d237 Alexei Starovoitov     2020-01-20  10794                         
        return -EINVAL;
be8704ff07d237 Alexei Starovoitov     2020-01-20  10795                         
}
be8704ff07d237 Alexei Starovoitov     2020-01-20  10796                 }
be8704ff07d237 Alexei Starovoitov     2020-01-20  10797                 if 
(!tgt_prog->jited) {
e33243ff1dd2cb Toke Høiland-Jørgensen 2020-07-15  10798                         
bpf_log(log, "Can attach to only JITed progs\n");
be8704ff07d237 Alexei Starovoitov     2020-01-20  10799                         
return -EINVAL;
be8704ff07d237 Alexei Starovoitov     2020-01-20  10800                 }
be8704ff07d237 Alexei Starovoitov     2020-01-20  10801                 if 
(tgt_prog->type == prog->type) {
be8704ff07d237 Alexei Starovoitov     2020-01-20  10802                         
/* Cannot fentry/fexit another fentry/fexit program.
be8704ff07d237 Alexei Starovoitov     2020-01-20  10803                         
 * Cannot attach program extension to another extension.
be8704ff07d237 Alexei Starovoitov     2020-01-20  10804                         
 * It's ok to attach fentry/fexit to extension program.
be8704ff07d237 Alexei Starovoitov     2020-01-20  10805                         
 */
e33243ff1dd2cb Toke Høiland-Jørgensen 2020-07-15  10806                         
bpf_log(log, "Cannot recursively attach\n");
be8704ff07d237 Alexei Starovoitov     2020-01-20  10807                         
return -EINVAL;
be8704ff07d237 Alexei Starovoitov     2020-01-20  10808                 }
be8704ff07d237 Alexei Starovoitov     2020-01-20  10809                 if 
(tgt_prog->type == BPF_PROG_TYPE_TRACING &&
be8704ff07d237 Alexei Starovoitov     2020-01-20  10810                     
prog_extension &&
be8704ff07d237 Alexei Starovoitov     2020-01-20  10811                     
(tgt_prog->expected_attach_type == BPF_TRACE_FENTRY ||
be8704ff07d237 Alexei Starovoitov     2020-01-20  10812                      
tgt_prog->expected_attach_type == BPF_TRACE_FEXIT)) {
be8704ff07d237 Alexei Starovoitov     2020-01-20  10813                         
/* Program extensions can extend all program types
be8704ff07d237 Alexei Starovoitov     2020-01-20  10814                         
 * except fentry/fexit. The reason is the following.
be8704ff07d237 Alexei Starovoitov     2020-01-20  10815                         
 * The fentry/fexit programs are used for performance
be8704ff07d237 Alexei Starovoitov     2020-01-20  10816                         
 * analysis, stats and can be attached to any program
be8704ff07d237 Alexei Starovoitov     2020-01-20  10817                         
 * type except themselves. When extension program is
be8704ff07d237 Alexei Starovoitov     2020-01-20  10818                         
 * replacing XDP function it is necessary to allow
be8704ff07d237 Alexei Starovoitov     2020-01-20  10819                         
 * performance analysis of all functions. Both original
be8704ff07d237 Alexei Starovoitov     2020-01-20  10820                         
 * XDP program and its program extension. Hence
be8704ff07d237 Alexei Starovoitov     2020-01-20  10821                         
 * attaching fentry/fexit to BPF_PROG_TYPE_EXT is
be8704ff07d237 Alexei Starovoitov     2020-01-20  10822                         
 * allowed. If extending of fentry/fexit was allowed it
be8704ff07d237 Alexei Starovoitov     2020-01-20  10823                         
 * would be possible to create long call chain
be8704ff07d237 Alexei Starovoitov     2020-01-20  10824                         
 * fentry->extension->fentry->extension beyond
be8704ff07d237 Alexei Starovoitov     2020-01-20  10825                         
 * reasonable stack size. Hence extending fentry is not
be8704ff07d237 Alexei Starovoitov     2020-01-20  10826                         
 * allowed.
be8704ff07d237 Alexei Starovoitov     2020-01-20  10827                         
 */
e33243ff1dd2cb Toke Høiland-Jørgensen 2020-07-15  10828                         
bpf_log(log, "Cannot extend fentry/fexit\n");
be8704ff07d237 Alexei Starovoitov     2020-01-20  10829                         
return -EINVAL;
be8704ff07d237 Alexei Starovoitov     2020-01-20  10830                 }
5b92a28aae4dd0 Alexei Starovoitov     2019-11-14  10831         } else {
be8704ff07d237 Alexei Starovoitov     2020-01-20  10832                 if 
(prog_extension) {
e33243ff1dd2cb Toke Høiland-Jørgensen 2020-07-15  10833                         
bpf_log(log, "Cannot replace kernel functions\n");
be8704ff07d237 Alexei Starovoitov     2020-01-20  10834                         
return -EINVAL;
be8704ff07d237 Alexei Starovoitov     2020-01-20  10835                 }
5b92a28aae4dd0 Alexei Starovoitov     2019-11-14  10836         }
f1b9509c2fb0ef Alexei Starovoitov     2019-10-30  10837  
f1b9509c2fb0ef Alexei Starovoitov     2019-10-30  10838         switch 
(prog->expected_attach_type) {
f1b9509c2fb0ef Alexei Starovoitov     2019-10-30  10839         case 
BPF_TRACE_RAW_TP:
5b92a28aae4dd0 Alexei Starovoitov     2019-11-14  10840                 if 
(tgt_prog) {
e33243ff1dd2cb Toke Høiland-Jørgensen 2020-07-15  10841                         
bpf_log(log,
5b92a28aae4dd0 Alexei Starovoitov     2019-11-14  10842                         
        "Only FENTRY/FEXIT progs are attachable to another BPF prog\n");
5b92a28aae4dd0 Alexei Starovoitov     2019-11-14  10843                         
return -EINVAL;
5b92a28aae4dd0 Alexei Starovoitov     2019-11-14  10844                 }
38207291604401 Martin KaFai Lau       2019-10-24  10845                 if 
(!btf_type_is_typedef(t)) {
e33243ff1dd2cb Toke Høiland-Jørgensen 2020-07-15  10846                         
bpf_log(log, "attach_btf_id %u is not a typedef\n",
38207291604401 Martin KaFai Lau       2019-10-24  10847                         
        btf_id);
38207291604401 Martin KaFai Lau       2019-10-24  10848                         
return -EINVAL;
38207291604401 Martin KaFai Lau       2019-10-24  10849                 }
f1b9509c2fb0ef Alexei Starovoitov     2019-10-30  10850                 if 
(strncmp(prefix, tname, sizeof(prefix) - 1)) {
e33243ff1dd2cb Toke Høiland-Jørgensen 2020-07-15  10851                         
bpf_log(log, "attach_btf_id %u points to wrong type name %s\n",
38207291604401 Martin KaFai Lau       2019-10-24  10852                         
        btf_id, tname);
38207291604401 Martin KaFai Lau       2019-10-24  10853                         
return -EINVAL;
38207291604401 Martin KaFai Lau       2019-10-24  10854                 }
38207291604401 Martin KaFai Lau       2019-10-24  10855                 tname 
+= sizeof(prefix) - 1;
5b92a28aae4dd0 Alexei Starovoitov     2019-11-14  10856                 t = 
btf_type_by_id(btf, t->type);
38207291604401 Martin KaFai Lau       2019-10-24  10857                 if 
(!btf_type_is_ptr(t))
38207291604401 Martin KaFai Lau       2019-10-24  10858                         
/* should never happen in valid vmlinux build */
38207291604401 Martin KaFai Lau       2019-10-24  10859                         
return -EINVAL;
5b92a28aae4dd0 Alexei Starovoitov     2019-11-14  10860                 t = 
btf_type_by_id(btf, t->type);
38207291604401 Martin KaFai Lau       2019-10-24  10861                 if 
(!btf_type_is_func_proto(t))
38207291604401 Martin KaFai Lau       2019-10-24  10862                         
/* should never happen in valid vmlinux build */
38207291604401 Martin KaFai Lau       2019-10-24  10863                         
return -EINVAL;
38207291604401 Martin KaFai Lau       2019-10-24  10864  
c2d0f6ffe7709e Toke Høiland-Jørgensen 2020-07-15  10865                 break;
15d83c4d7cef5c Yonghong Song          2020-05-09  10866         case 
BPF_TRACE_ITER:
15d83c4d7cef5c Yonghong Song          2020-05-09  10867                 if 
(!btf_type_is_func(t)) {
e33243ff1dd2cb Toke Høiland-Jørgensen 2020-07-15  10868                         
bpf_log(log, "attach_btf_id %u is not a function\n",
15d83c4d7cef5c Yonghong Song          2020-05-09  10869                         
        btf_id);
15d83c4d7cef5c Yonghong Song          2020-05-09  10870                         
return -EINVAL;
15d83c4d7cef5c Yonghong Song          2020-05-09  10871                 }
15d83c4d7cef5c Yonghong Song          2020-05-09  10872                 t = 
btf_type_by_id(btf, t->type);
15d83c4d7cef5c Yonghong Song          2020-05-09  10873                 if 
(!btf_type_is_func_proto(t))
15d83c4d7cef5c Yonghong Song          2020-05-09  10874                         
return -EINVAL;
c2d0f6ffe7709e Toke Høiland-Jørgensen 2020-07-15  10875                 ret = 
btf_distill_func_proto(log, btf, t, tname, fmodel);
c2d0f6ffe7709e Toke Høiland-Jørgensen 2020-07-15  10876                 if (ret)
15d83c4d7cef5c Yonghong Song          2020-05-09  10877                         
return ret;
c2d0f6ffe7709e Toke Høiland-Jørgensen 2020-07-15  10878                 break;
be8704ff07d237 Alexei Starovoitov     2020-01-20  10879         default:
be8704ff07d237 Alexei Starovoitov     2020-01-20  10880                 if 
(!prog_extension)
be8704ff07d237 Alexei Starovoitov     2020-01-20  10881                         
return -EINVAL;
be8704ff07d237 Alexei Starovoitov     2020-01-20  10882                 /* 
fallthrough */
ae24082331d9bb KP Singh               2020-03-04  10883         case 
BPF_MODIFY_RETURN:
9e4e01dfd3254c KP Singh               2020-03-29  10884         case 
BPF_LSM_MAC:
fec56f5890d93f Alexei Starovoitov     2019-11-14  10885         case 
BPF_TRACE_FENTRY:
fec56f5890d93f Alexei Starovoitov     2019-11-14  10886         case 
BPF_TRACE_FEXIT:
fec56f5890d93f Alexei Starovoitov     2019-11-14  10887                 if 
(!btf_type_is_func(t)) {
e33243ff1dd2cb Toke Høiland-Jørgensen 2020-07-15  10888                         
bpf_log(log, "attach_btf_id %u is not a function\n",
fec56f5890d93f Alexei Starovoitov     2019-11-14  10889                         
        btf_id);
fec56f5890d93f Alexei Starovoitov     2019-11-14  10890                         
return -EINVAL;
fec56f5890d93f Alexei Starovoitov     2019-11-14  10891                 }
be8704ff07d237 Alexei Starovoitov     2020-01-20  10892                 if 
(prog_extension &&
e33243ff1dd2cb Toke Høiland-Jørgensen 2020-07-15  10893                     
btf_check_type_match(log, prog, btf, t))
be8704ff07d237 Alexei Starovoitov     2020-01-20  10894                         
return -EINVAL;
5b92a28aae4dd0 Alexei Starovoitov     2019-11-14  10895                 t = 
btf_type_by_id(btf, t->type);
fec56f5890d93f Alexei Starovoitov     2019-11-14  10896                 if 
(!btf_type_is_func_proto(t))
fec56f5890d93f Alexei Starovoitov     2019-11-14  10897                         
return -EINVAL;
c2d0f6ffe7709e Toke Høiland-Jørgensen 2020-07-15  10898  
cc8571ec751a3a Toke Høiland-Jørgensen 2020-07-15  10899                 if 
((prog->aux->tgt_prog_type &&
cc8571ec751a3a Toke Høiland-Jørgensen 2020-07-15 @10900                      
prog->aux->tgt_prog_type != tgt_prog->type) ||
                                                                                
                         ^^^^^^^^^^^^^^

cc8571ec751a3a Toke Høiland-Jørgensen 2020-07-15  10901                     
(prog->aux->tgt_attach_type &&
cc8571ec751a3a Toke Høiland-Jørgensen 2020-07-15  10902                      
prog->aux->tgt_attach_type != tgt_prog->expected_attach_type))
                                                                                
                           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Not checked.

cc8571ec751a3a Toke Høiland-Jørgensen 2020-07-15  10903                         
return -EINVAL;
cc8571ec751a3a Toke Høiland-Jørgensen 2020-07-15  10904  
c2d0f6ffe7709e Toke Høiland-Jørgensen 2020-07-15  10905                 if 
(tgt_prog && conservative)
5b92a28aae4dd0 Alexei Starovoitov     2019-11-14  10906                         
t = NULL;
c2d0f6ffe7709e Toke Høiland-Jørgensen 2020-07-15  10907  
c2d0f6ffe7709e Toke Høiland-Jørgensen 2020-07-15  10908                 ret = 
btf_distill_func_proto(log, btf, t, tname, fmodel);
fec56f5890d93f Alexei Starovoitov     2019-11-14  10909                 if (ret 
< 0)
c2d0f6ffe7709e Toke Høiland-Jørgensen 2020-07-15  10910                         
return ret;
c2d0f6ffe7709e Toke Høiland-Jørgensen 2020-07-15  10911  
5b92a28aae4dd0 Alexei Starovoitov     2019-11-14  10912                 if 
(tgt_prog) {
e9eeec58c992c4 Yonghong Song          2019-12-04  10913                         
if (subprog == 0)
e9eeec58c992c4 Yonghong Song          2019-12-04  10914                         
        addr = (long) tgt_prog->bpf_func;
e9eeec58c992c4 Yonghong Song          2019-12-04  10915                         
else
5b92a28aae4dd0 Alexei Starovoitov     2019-11-14  10916                         
        addr = (long) tgt_prog->aux->func[subprog]->bpf_func;
5b92a28aae4dd0 Alexei Starovoitov     2019-11-14  10917                 } else {
fec56f5890d93f Alexei Starovoitov     2019-11-14  10918                         
addr = kallsyms_lookup_name(tname);
fec56f5890d93f Alexei Starovoitov     2019-11-14  10919                         
if (!addr) {
e33243ff1dd2cb Toke Høiland-Jørgensen 2020-07-15  10920                         
        bpf_log(log,
fec56f5890d93f Alexei Starovoitov     2019-11-14  10921                         
                "The address of function %s cannot be found\n",
fec56f5890d93f Alexei Starovoitov     2019-11-14  10922                         
                tname);
c2d0f6ffe7709e Toke Høiland-Jørgensen 2020-07-15  10923                         
        return -ENOENT;
fec56f5890d93f Alexei Starovoitov     2019-11-14  10924                         
}
5b92a28aae4dd0 Alexei Starovoitov     2019-11-14  10925                 }
c2d0f6ffe7709e Toke Høiland-Jørgensen 2020-07-15  10926                 break;
c2d0f6ffe7709e Toke Høiland-Jørgensen 2020-07-15  10927         }
18644cec714aab Alexei Starovoitov     2020-05-28  10928  
c2d0f6ffe7709e Toke Høiland-Jørgensen 2020-07-15  10929         *tgt_addr = 
addr;
c2d0f6ffe7709e Toke Høiland-Jørgensen 2020-07-15  10930         if (tgt_name)
c2d0f6ffe7709e Toke Høiland-Jørgensen 2020-07-15  10931                 
*tgt_name = tname;
c2d0f6ffe7709e Toke Høiland-Jørgensen 2020-07-15  10932         if (tgt_type)
c2d0f6ffe7709e Toke Høiland-Jørgensen 2020-07-15  10933                 
*tgt_type = t;
c2d0f6ffe7709e Toke Høiland-Jørgensen 2020-07-15  10934         return 0;
18644cec714aab Alexei Starovoitov     2020-05-28  10935  }

---
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