Messages in this thread | | | From | Arnd Bergmann <> | Date | Thu, 2 Nov 2017 17:14:00 +0100 | Subject | Re: [PATCH 2/2] [net-next] bpf: fix out-of-bounds access warning in bpf_check |
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On Thu, Nov 2, 2017 at 4:59 PM, Alexei Starovoitov <alexei.starovoitov@gmail.com> 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.
Arnd
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