diff options
Diffstat (limited to 'tools/testing/selftests/bpf/test_verifier.c')
| -rw-r--r-- | tools/testing/selftests/bpf/test_verifier.c | 39 |
1 files changed, 39 insertions, 0 deletions
diff --git a/tools/testing/selftests/bpf/test_verifier.c b/tools/testing/selftests/bpf/test_verifier.c index 7fe897c66d81..f9d553fbf68a 100644 --- a/tools/testing/selftests/bpf/test_verifier.c +++ b/tools/testing/selftests/bpf/test_verifier.c @@ -425,6 +425,45 @@ static void bpf_fill_torturous_jumps(struct bpf_test *self) } } +static void bpf_fill_big_prog_with_loop_1(struct bpf_test *self) +{ + struct bpf_insn *insn = self->fill_insns; + /* This test was added to catch a specific use after free + * error, which happened upon BPF program reallocation. + * Reallocation is handled by core.c:bpf_prog_realloc, which + * reuses old memory if page boundary is not crossed. The + * value of `len` is chosen to cross this boundary on bpf_loop + * patching. + */ + const int len = getpagesize() - 25; + int callback_load_idx; + int callback_idx; + int i = 0; + + insn[i++] = BPF_ALU64_IMM(BPF_MOV, BPF_REG_1, 1); + callback_load_idx = i; + insn[i++] = BPF_RAW_INSN(BPF_LD | BPF_IMM | BPF_DW, + BPF_REG_2, BPF_PSEUDO_FUNC, 0, + 777 /* filled below */); + insn[i++] = BPF_RAW_INSN(0, 0, 0, 0, 0); + insn[i++] = BPF_ALU64_IMM(BPF_MOV, BPF_REG_3, 0); + insn[i++] = BPF_ALU64_IMM(BPF_MOV, BPF_REG_4, 0); + insn[i++] = BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, BPF_FUNC_loop); + + while (i < len - 3) + insn[i++] = BPF_ALU64_IMM(BPF_MOV, BPF_REG_0, 0); + insn[i++] = BPF_EXIT_INSN(); + + callback_idx = i; + insn[i++] = BPF_ALU64_IMM(BPF_MOV, BPF_REG_0, 0); + insn[i++] = BPF_EXIT_INSN(); + + insn[callback_load_idx].imm = callback_idx - callback_load_idx - 1; + self->func_info[1].insn_off = callback_idx; + self->prog_len = i; + assert(i == len); +} + /* BPF_SK_LOOKUP contains 13 instructions, if you need to fix up maps */ #define BPF_SK_LOOKUP(func) \ /* struct bpf_sock_tuple tuple = {} */ \ |