selftests/bpf: Use bpf_num_possible_cpus() in per-cpu map allocations

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bpf_map_value_size() uses num_possible_cpus() to determine map size, but
some of the tests only allocate enough memory for online cpus. This
results in out-of-bound writes in userspace during bpf(BPF_MAP_LOOKUP_ELEM)
syscalls in cases when number of online cpus is lower than the number of
possible cpus. Fix by switching from get_nprocs_conf() to
bpf_num_possible_cpus() when determining the number of processors in
these tests (test_progs/netcnt and test_cgroup_storage).

Signed-off-by: Artem Savkov <asavkov@redhat.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20220406085408.339336-1-asavkov@redhat.com

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Artem Savkov 2022-04-06 10:54:08 +02:00 • committed by Andrii Nakryiko

parent a8d600f6bc

commit ebaf24c589

2 changed files with 3 additions and 2 deletions

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2

tools/testing/selftests/bpf/prog_tests/netcnt.c

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3

tools/testing/selftests/bpf/test_cgroup_storage.c

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