diff options
| author | Alexei Starovoitov <ast@kernel.org> | 2023-11-01 22:30:27 -0700 |
|---|---|---|
| committer | Alexei Starovoitov <ast@kernel.org> | 2023-11-01 22:30:28 -0700 |
| commit | b479d38ba959a8e3ffc4d9f760a9f2e4b9027e66 (patch) | |
| tree | fb460b6b1633d37877ab1ffe856a8d9ca5b30d21 | |
| parent | 05670f81d1287c40ec861186e4c4e3401013e7fb (diff) | |
| parent | 85eb035e6cfd615071256592e1dbe72c1d99c24b (diff) | |
Merge branch 'bpf-fix-incorrect-immediate-spill'
Hao Sun says:
====================
bpf: Fix incorrect immediate spill
Immediate is incorrectly cast to u32 before being spilled, losing sign
information. The range information is incorrect after load again. Fix
immediate spill by remove the cast. The second patch add a test case
for this.
Signed-off-by: Hao Sun <sunhao.th@gmail.com>
---
Changes in v3:
- Change the expected log to fix the test case
- Link to v2: https://lore.kernel.org/r/20231101-fix-check-stack-write-v2-0-cb7c17b869b0@gmail.com
Changes in v2:
- Add fix and cc tags.
- Link to v1: https://lore.kernel.org/r/20231026-fix-check-stack-write-v1-0-6b325ef3ce7e@gmail.com
---
====================
Link: https://lore.kernel.org/r/20231101-fix-check-stack-write-v3-0-f05c2b1473d5@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
| -rw-r--r-- | kernel/bpf/verifier.c | 2 | ||||
| -rw-r--r-- | tools/testing/selftests/bpf/verifier/bpf_st_mem.c | 32 |
2 files changed, 33 insertions, 1 deletions
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 8c91e0e54e27..014b4d1ef408 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -4674,7 +4674,7 @@ static int check_stack_write_fixed_off(struct bpf_verifier_env *env, insn->imm != 0 && env->bpf_capable) { struct bpf_reg_state fake_reg = {}; - __mark_reg_known(&fake_reg, (u32)insn->imm); + __mark_reg_known(&fake_reg, insn->imm); fake_reg.type = SCALAR_VALUE; save_register_state(state, spi, &fake_reg, size); } else if (reg && is_spillable_regtype(reg->type)) { diff --git a/tools/testing/selftests/bpf/verifier/bpf_st_mem.c b/tools/testing/selftests/bpf/verifier/bpf_st_mem.c index 3af2501082b2..b616575c3b00 100644 --- a/tools/testing/selftests/bpf/verifier/bpf_st_mem.c +++ b/tools/testing/selftests/bpf/verifier/bpf_st_mem.c @@ -65,3 +65,35 @@ .expected_attach_type = BPF_SK_LOOKUP, .runs = -1, }, +{ + "BPF_ST_MEM stack imm sign", + /* Check if verifier correctly reasons about sign of an + * immediate spilled to stack by BPF_ST instruction. + * + * fp[-8] = -44; + * r0 = fp[-8]; + * if r0 s< 0 goto ret0; + * r0 = -1; + * exit; + * ret0: + * r0 = 0; + * exit; + */ + .insns = { + BPF_ST_MEM(BPF_DW, BPF_REG_10, -8, -44), + BPF_LDX_MEM(BPF_DW, BPF_REG_0, BPF_REG_10, -8), + BPF_JMP_IMM(BPF_JSLT, BPF_REG_0, 0, 2), + BPF_MOV64_IMM(BPF_REG_0, -1), + BPF_EXIT_INSN(), + BPF_MOV64_IMM(BPF_REG_0, 0), + BPF_EXIT_INSN(), + }, + /* Use prog type that requires return value in range [0, 1] */ + .prog_type = BPF_PROG_TYPE_SK_LOOKUP, + .expected_attach_type = BPF_SK_LOOKUP, + .result = VERBOSE_ACCEPT, + .runs = -1, + .errstr = "0: (7a) *(u64 *)(r10 -8) = -44 ; R10=fp0 fp-8_w=-44\ + 2: (c5) if r0 s< 0x0 goto pc+2\ + R0_w=-44", +}, |