On Thu, 2 Nov 2017 17:14:00 +0100, Arnd Bergmann wrote: > On Thu, Nov 2, 2017 at 4:59 PM, Alexei Starovoitov wrote: > > On Thu, Nov 02, 2017 at 12:05:52PM +0100, Arnd Bergmann wrote: > >> diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c > >> index 750aff880ecb..debb60ad08ee 100644 > >> --- a/kernel/bpf/verifier.c > >> +++ b/kernel/bpf/verifier.c > >> @@ -4447,6 +4447,10 @@ int bpf_check(struct bpf_prog **prog, union > >> bpf_attr *attr) > >> struct bpf_verifer_log *log; > >> int ret = -EINVAL; > >> > >> + /* no program is valid */ > >> + if (ARRAY_SIZE(bpf_verifier_ops) == 0) > >> + return -EINVAL; > > > > sorry I don't see how bpf_verifier_ops can be empty. > > Did you mix it up with your previous patch when you made bpf_analyzer_ops > > empty? > > I confused the two a couple of times while creating the patches, but > I'm still fairly > sure I got it right in the end: > > bpf_verifier_ops is an array that gets generated by including > linux/bpf_types.h. > That file has two kinds of entries: > > - BPF_MAP_TYPE() entries are left out, as that macro is defined to an > empty string > here. > > - BPF_PROG_TYPE() entries are conditional depending on CONFIG_NET and > CONFIG_BPF_EVENTS. In the configuration that produces the warning, > both are disabled.
Right. My preferred fix was to add a NULL entry to the table so it's never empty, but this is OK too. Thanks!
