bpf: Use array_map_meta_equal for percpu array inner map replacement

2026-05-14T15:18:50Z

percpu_array_map_ops.map_meta_equal points to the generic bpf_map_meta_equal(), which does not compare max_entries. When a percpu array serves as an inner map, replacing it with one that has fewer max_entries bypasses the check. Since percpu_array_map_gen_lookup() inlines the original template's index_mask as a JIT immediate, a lookup on the replacement map can access pptrs[] out of bounds. Point percpu_array_map_ops.map_meta_equal to array_map_meta_equal(), which already enforces the max_entries equality check. Add a selftest to verify that replacing a percpu array inner map with a differently-sized one is rejected. Fixes: db69718b8efa ("bpf: inline bpf_map_lookup_elem() for PERCPU_ARRAY maps") Signed-off-by: Guannan Wang Acked-by: Mykyta Yatsenko Link: https://lore.kernel.org/r/20260514074454.77491-1-wgnbuaa@gmail.com Signed-off-by: Alexei Starovoitov

wireguard-linux/tools/testing/selftests/bpf/prog_tests/percpu_array_inner_map.c, branch stable

bpf: Use array_map_meta_equal for percpu array inner map replacement