selftests/bpf: add tests for stack_zero tracking

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>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

diff --git a/tools/testing/selftests/bpf/test_verifier.c b/tools/testing/selftests/bpf/test_verifier.c
index 88f389c6ec4847a746bf21929899665c8762abb6..eaf294822a8f2460af2ca871fbe75e471265a5c8 100644 (file)
--- 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)