[PATCH bpf-next 05/13] selftests/bpf: add tests for stack_zero tracking
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STALE3230d
REVIEWED: 1 (1M)
From: Alexei Starovoitov <ast@kernel.org>
Date: 2017-12-15 01:55:23
Subsystem:
bpf [general] (safe dynamic programs and tools), bpf [selftests] (test runners & infrastructure), kernel selftest framework, the rest · Maintainers:
Alexei Starovoitov, Daniel Borkmann, Andrii Nakryiko, Eduard Zingerman, Kumar Kartikeya Dwivedi, Shuah Khan, Shuah Khan, Linus Torvalds
1 review trailer (1 from subsystem maintainers).
From: Alexei Starovoitov <redacted> adjust two tests, since verifier got smarter and add new one to test stack_zero logic Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Daniel Borkmann <daniel@iogearbox.net> --- tools/testing/selftests/bpf/test_verifier.c | 66 ++++++++++++++++++++++++++++- 1 file changed, 64 insertions(+), 2 deletions(-)
diff --git a/tools/testing/selftests/bpf/test_verifier.c b/tools/testing/selftests/bpf/test_verifier.c
index 88f389c6ec48..eaf294822a8f 100644
--- a/tools/testing/selftests/bpf/test_verifier.c
+++ b/tools/testing/selftests/bpf/test_verifier.c@@ -5649,7 +5649,7 @@ static struct bpf_test tests[] = { "helper access to variable memory: size > 0 not allowed on NULL (ARG_PTR_TO_MEM_OR_NULL)", .insns = { BPF_MOV64_IMM(BPF_REG_1, 0), - BPF_MOV64_IMM(BPF_REG_2, 0), + BPF_MOV64_IMM(BPF_REG_2, 1), BPF_STX_MEM(BPF_DW, BPF_REG_10, BPF_REG_2, -128), BPF_LDX_MEM(BPF_DW, BPF_REG_2, BPF_REG_10, -128), BPF_ALU64_IMM(BPF_AND, BPF_REG_2, 64),
@@ -5884,7 +5884,7 @@ static struct bpf_test tests[] = { BPF_STX_MEM(BPF_DW, BPF_REG_10, BPF_REG_0, -24), BPF_STX_MEM(BPF_DW, BPF_REG_10, BPF_REG_0, -16), BPF_STX_MEM(BPF_DW, BPF_REG_10, BPF_REG_0, -8), - BPF_MOV64_IMM(BPF_REG_2, 0), + BPF_MOV64_IMM(BPF_REG_2, 1), BPF_STX_MEM(BPF_DW, BPF_REG_10, BPF_REG_2, -128), BPF_LDX_MEM(BPF_DW, BPF_REG_2, BPF_REG_10, -128), BPF_ALU64_IMM(BPF_AND, BPF_REG_2, 63),
@@ -9056,6 +9056,68 @@ static struct bpf_test tests[] = { .result = ACCEPT, .prog_type = BPF_PROG_TYPE_SCHED_CLS, }, + { + "calls: caller stack init to zero or map_value_or_null", + .insns = { + BPF_MOV64_IMM(BPF_REG_0, 0), + BPF_STX_MEM(BPF_DW, BPF_REG_10, BPF_REG_0, -8), + BPF_MOV64_REG(BPF_REG_2, BPF_REG_10), + BPF_ALU64_IMM(BPF_ADD, BPF_REG_2, -8), + BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 1, 0, 4), + /* fetch map_value_or_null or const_zero from stack */ + BPF_LDX_MEM(BPF_DW, BPF_REG_0, BPF_REG_10, -8), + BPF_JMP_IMM(BPF_JEQ, BPF_REG_0, 0, 1), + /* store into map_value */ + BPF_ST_MEM(BPF_W, BPF_REG_0, 0, 0), + BPF_EXIT_INSN(), + + /* subprog 1 */ + /* if (ctx == 0) return; */ + BPF_JMP_IMM(BPF_JEQ, BPF_REG_1, 0, 8), + /* else bpf_map_lookup() and *(fp - 8) = r0 */ + BPF_MOV64_REG(BPF_REG_6, BPF_REG_2), + BPF_MOV64_REG(BPF_REG_2, BPF_REG_10), + BPF_ALU64_IMM(BPF_ADD, BPF_REG_2, -8), + BPF_LD_MAP_FD(BPF_REG_1, 0), + BPF_ST_MEM(BPF_DW, BPF_REG_10, -8, 0), + BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, + BPF_FUNC_map_lookup_elem), + /* write map_value_ptr_or_null into stack frame of main prog at fp-8 */ + BPF_STX_MEM(BPF_DW, BPF_REG_6, BPF_REG_0, 0), + BPF_EXIT_INSN(), + }, + .fixup_map1 = { 13 }, + .result = ACCEPT, + .prog_type = BPF_PROG_TYPE_XDP, + }, + { + "calls: stack init to zero and pruning", + .insns = { + /* first make allocated_stack 16 byte */ + BPF_ST_MEM(BPF_DW, BPF_REG_10, -16, 0), + /* now fork the execution such that the false branch + * of JGT insn will be verified second and it skisp zero + * init of fp-8 stack slot. If stack liveness marking + * is missing live_read marks from call map_lookup + * processing then pruning will incorrectly assume + * that fp-8 stack slot was unused in the fall-through + * branch and will accept the program incorrectly + */ + BPF_JMP_IMM(BPF_JGT, BPF_REG_1, 2, 2), + BPF_ST_MEM(BPF_DW, BPF_REG_10, -8, 0), + BPF_JMP_IMM(BPF_JA, 0, 0, 0), + BPF_MOV64_REG(BPF_REG_2, BPF_REG_10), + BPF_ALU64_IMM(BPF_ADD, BPF_REG_2, -8), + BPF_LD_MAP_FD(BPF_REG_1, 0), + BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, + BPF_FUNC_map_lookup_elem), + BPF_EXIT_INSN(), + }, + .fixup_map2 = { 6 }, + .errstr = "invalid indirect read from stack off -8+0 size 8", + .result = REJECT, + .prog_type = BPF_PROG_TYPE_XDP, + }, }; static int probe_filter_length(const struct bpf_insn *fp)
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2.9.5