Check that verifier tracks the value of 'imm' spilled to stack by
BPF_ST_MEM instruction. Cover the following cases:
- write of non-zero constant to stack;
- write of a zero constant to stack.
Signed-off-by: Eduard Zingerman <eddyz87@xxxxxxxxx>
---
.../selftests/bpf/verifier/bpf_st_mem.c | 29 +++++++++++++++++++
1 file changed, 29 insertions(+)
create mode 100644 tools/testing/selftests/bpf/verifier/bpf_st_mem.c
diff --git a/tools/testing/selftests/bpf/verifier/bpf_st_mem.c b/tools/testing/selftests/bpf/verifier/bpf_st_mem.c
new file mode 100644
index 000000000000..d3aa293f1a9d
--- /dev/null
+++ b/tools/testing/selftests/bpf/verifier/bpf_st_mem.c
@@ -0,0 +1,29 @@
+{
+ "BPF_ST_MEM stack imm non-zero",
+ .insns = {
+ BPF_ST_MEM(BPF_DW, BPF_REG_10, -8, 42),
+ BPF_LDX_MEM(BPF_DW, BPF_REG_0, BPF_REG_10, -8),
+ BPF_ALU64_IMM(BPF_ADD, BPF_REG_0, -42),
+ /* if value is tracked correctly R0 is zero */
+ BPF_EXIT_INSN(),
+ },
+ .result = ACCEPT,
+},
+{
+ "BPF_ST_MEM stack imm zero",
+ .insns = {
+ /* mark stack 0000 0000 */
+ BPF_ST_MEM(BPF_DW, BPF_REG_10, -8, 0),
+ /* read and sum a few bytes */
+ BPF_MOV64_IMM(BPF_REG_0, 0),
+ BPF_LDX_MEM(BPF_B, BPF_REG_1, BPF_REG_10, -8),
+ BPF_ALU64_REG(BPF_ADD, BPF_REG_0, BPF_REG_1),
+ BPF_LDX_MEM(BPF_B, BPF_REG_1, BPF_REG_10, -4),
+ BPF_ALU64_REG(BPF_ADD, BPF_REG_0, BPF_REG_1),
+ BPF_LDX_MEM(BPF_B, BPF_REG_1, BPF_REG_10, -1),
+ BPF_ALU64_REG(BPF_ADD, BPF_REG_0, BPF_REG_1),
+ /* if value is tracked correctly R0 is zero */
+ BPF_EXIT_INSN(),
+ },
+ .result = ACCEPT,
+},
--
2.39.0
