// SPDX-License-Identifier: GPL-2.0 #include "vmlinux.h" #include <bpf/bpf_helpers.h> #include "bpf_misc.h" #ifndef __clang__ #pragma GCC diagnostic ignored "-Warray-bounds" #endif char _license[] SEC("license") = "GPL"; struct { __uint(type, BPF_MAP_TYPE_HASH); __uint(max_entries, 1); __type(key, u64); __type(value, u64); } m_hash SEC(".maps"); SEC("?raw_tp") __failure __msg("R8 invalid mem access 'map_value_or_null") int jeq_infer_not_null_ptr_to_btfid(void *ctx) { struct bpf_map *map = (struct bpf_map *)&m_hash; struct bpf_map *inner_map = map->inner_map_meta; u64 key = 0, ret = 0, *val; val = bpf_map_lookup_elem(map, &key); /* Do not mark ptr as non-null if one of them is * PTR_TO_BTF_ID (R9), reject because of invalid * access to map value (R8). * * Here, we need to inline those insns to access * R8 directly, since compiler may use other reg * once it figures out val==inner_map. */ asm volatile("r8 = %[val];\n" "r9 = %[inner_map];\n" "if r8 != r9 goto +1;\n" "%[ret] = *(u64 *)(r8 +0);\n" : [ret] "+r"(ret) : [inner_map] "r"(inner_map), [val] "r"(val) : "r8", "r9"); return ret; }