[PATCH bpf-next 2/2] selftests/bpf: additional stack depth tests

[Alexei Starovoitov]

to test inner logic of stack depth tracking

Signed-off-by: Alexei Starovoitov <a...@kernel.org>
---
 tools/testing/selftests/bpf/test_verifier.c | 50 +++++++++++++++++++++++++++++
 1 file changed, 50 insertions(+)

diff --git a/tools/testing/selftests/bpf/test_verifier.c 
b/tools/testing/selftests/bpf/test_verifier.c
index 71fb0be81b78..e0b21c95c3bc 100644
--- a/tools/testing/selftests/bpf/test_verifier.c
+++ b/tools/testing/selftests/bpf/test_verifier.c
@@ -8764,6 +8764,56 @@ static struct bpf_test tests[] = {
                .result = REJECT,
        },
        {
+               "calls: stack depth check using three frames. test1",
+               .insns = {
+                       /* main */
+                       BPF_RAW_INSN(BPF_JMP|BPF_CALL, 0, 1, 0, 4), /* call A */
+                       BPF_RAW_INSN(BPF_JMP|BPF_CALL, 0, 1, 0, 5), /* call B */
+                       BPF_ST_MEM(BPF_B, BPF_REG_10, -32, 0),
+                       BPF_MOV64_IMM(BPF_REG_0, 0),
+                       BPF_EXIT_INSN(),
+                       /* A */
+                       BPF_ST_MEM(BPF_B, BPF_REG_10, -256, 0),
+                       BPF_EXIT_INSN(),
+                       /* B */
+                       BPF_RAW_INSN(BPF_JMP|BPF_CALL, 0, 1, 0, -3), /* call A 
*/
+                       BPF_ST_MEM(BPF_B, BPF_REG_10, -64, 0),
+                       BPF_EXIT_INSN(),
+               },
+               .prog_type = BPF_PROG_TYPE_XDP,
+               /* though stack_main=32, stack_A=256, stack_B=64
+                * and max(main+A, main+A+B) < 512 the program is rejected
+                * since stack tracking is conservative
+                * frame[0]=32, frame[1]=256, frame[2]=256
+                */
+               .errstr = "combined stack size",
+               .result = REJECT,
+       },
+       {
+               "calls: stack depth check using three frames. test2",
+               .insns = {
+                       /* main */
+                       BPF_RAW_INSN(BPF_JMP|BPF_CALL, 0, 1, 0, 4), /* call A */
+                       BPF_RAW_INSN(BPF_JMP|BPF_CALL, 0, 1, 0, 5), /* call B */
+                       BPF_ST_MEM(BPF_B, BPF_REG_10, -32, 0),
+                       BPF_MOV64_IMM(BPF_REG_0, 0),
+                       BPF_EXIT_INSN(),
+                       /* A */
+                       BPF_ST_MEM(BPF_B, BPF_REG_10, -64, 0),
+                       BPF_EXIT_INSN(),
+                       /* B */
+                       BPF_RAW_INSN(BPF_JMP|BPF_CALL, 0, 1, 0, -3), /* call A 
*/
+                       BPF_ST_MEM(BPF_B, BPF_REG_10, -256, 0),
+                       BPF_EXIT_INSN(),
+               },
+               .prog_type = BPF_PROG_TYPE_XDP,
+               /* though stack_main=32, stack_A=64, stack_B=256
+                * and max(main+A, main+A+B) < 512 the program is accepted
+                * since frame[0]=32, frame[1]=256, frame[2]=64
+                */
+               .result = ACCEPT,
+       },
+       {
                "calls: spill into caller stack frame",
                .insns = {
                        BPF_ST_MEM(BPF_DW, BPF_REG_10, -8, 0),
-- 
2.9.5