1 /* 2 * Buggy verifier accepted the program below while not patching BPF_PSEUDO_FUNC 3 * load instruction to contain a real address. Which resulted in a function call 4 * to a bogus address. 5 */ 6 { 7 "BPF_PSEUDO_FUNC reference to the main program", 8 .insns = { 9 /* r6 = bpf_map_lookup_elem(&timer_map, &(int){0}); */ 10 BPF_ST_MEM(BPF_W, BPF_REG_10, -4, 0), 11 BPF_MOV64_REG(BPF_REG_2, BPF_REG_10), 12 BPF_ALU64_IMM(BPF_ADD, BPF_REG_2, -4), 13 BPF_LD_MAP_FD(BPF_REG_1, 0), 14 BPF_EMIT_CALL(BPF_FUNC_map_lookup_elem), 15 BPF_JMP_IMM(BPF_JEQ, BPF_REG_0, 0, 10), 16 BPF_MOV64_REG(BPF_REG_6, BPF_REG_0), 17 /* bpf_timer_init(r6, &timer_map, 0); */ 18 BPF_MOV64_REG(BPF_REG_1, BPF_REG_6), 19 BPF_LD_MAP_FD(BPF_REG_2, 0), 20 BPF_MOV64_IMM(BPF_REG_3, 0), 21 BPF_EMIT_CALL(BPF_FUNC_timer_init), 22 /* bpf_timer_set_callback(r6, <insn #0>); */ 23 BPF_MOV64_REG(BPF_REG_1, BPF_REG_6), 24 BPF_RAW_INSN(BPF_LD | BPF_IMM | BPF_DW, BPF_REG_2, BPF_PSEUDO_FUNC, 0, -15), 25 BPF_RAW_INSN(0, 0, 0, 0, 0), 26 BPF_EMIT_CALL(BPF_FUNC_timer_set_callback), 27 BPF_MOV64_IMM(BPF_REG_0, 0), 28 BPF_EXIT_INSN(), 29 }, 30 .prog_type = BPF_PROG_TYPE_TRACEPOINT, 31 .fixup_map_timer = { 3, 9 }, 32 .result = REJECT, 33 .errstr = "callback function cannot be the main program", 34 .func_info = { { 0, 4 /* main_prog */ } }, 35 .func_info_cnt = 1, 36 .btf_strings = "\0int\0ctx\0main_prog", 37 .btf_types = { 38 /* 1: int */ BTF_TYPE_INT_ENC(1, BTF_INT_SIGNED, 0, 32, 4), 39 /* 2: void* */ BTF_PTR_ENC(0), 40 /* 3: int __(void *) */ BTF_FUNC_PROTO_ENC(1, 1), 41 BTF_FUNC_PROTO_ARG_ENC(5, 2), 42 /* 4: main_prog */ BTF_FUNC_ENC(9, 3), 43 BTF_END_RAW 44 } 45 }, 46