From: Toke Høiland-Jørgensen toke@redhat.com
commit bc23d0e3f717ced21fbfacab3ab887d55e5ba367 upstream.
When the kernel is built with CONFIG_DEBUG_PER_CPU_MAPS, the cpumap code can trigger a spurious warning if CONFIG_CPUMASK_OFFSTACK is also set. This happens because in this configuration, NR_CPUS can be larger than nr_cpumask_bits, so the initial check in cpu_map_alloc() is not sufficient to guard against hitting the warning in cpumask_check().
Fix this by explicitly checking the supplied key against the nr_cpumask_bits variable before calling cpu_possible().
Fixes: 6710e1126934 ("bpf: introduce new bpf cpu map type BPF_MAP_TYPE_CPUMAP") Reported-by: Xiumei Mu xmu@redhat.com Signed-off-by: Toke Høiland-Jørgensen toke@redhat.com Signed-off-by: Alexei Starovoitov ast@kernel.org Tested-by: Xiumei Mu xmu@redhat.com Acked-by: Jesper Dangaard Brouer brouer@redhat.com Acked-by: Song Liu songliubraving@fb.com Link: https://lore.kernel.org/bpf/20200416083120.453718-1-toke@redhat.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- kernel/bpf/cpumap.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/kernel/bpf/cpumap.c b/kernel/bpf/cpumap.c index 3c18260..61fbcae 100644 --- a/kernel/bpf/cpumap.c +++ b/kernel/bpf/cpumap.c @@ -455,7 +455,7 @@ static int cpu_map_update_elem(struct bpf_map *map, void *key, void *value, return -EOVERFLOW;
/* Make sure CPU is a valid possible cpu */ - if (!cpu_possible(key_cpu)) + if (key_cpu >= nr_cpumask_bits || !cpu_possible(key_cpu)) return -ENODEV;
if (qsize == 0) {