This test case is equivalent to the following pseudo-code. It checks that
the verifier does not complain on line 6 and recognizes that ptr isn't
null.
1: ptr = bpf_map_lookup_elem(map, &key);
2: ret = subprog(ptr) {
3: return ptr != NULL;
4: }
5: if (ret)
6: value = *ptr;
Signed-off-by: Paul Chaignon <paul.chaignon@xxxxxxxxxx>
---
tools/testing/selftests/bpf/verifier/calls.c | 25 ++++++++++++++++++++
1 file changed, 25 insertions(+)
diff --git a/tools/testing/selftests/bpf/verifier/calls.c b/tools/testing/selftests/bpf/verifier/calls.c
index fb11240b758b..9093a8f64dc6 100644
--- a/tools/testing/selftests/bpf/verifier/calls.c
+++ b/tools/testing/selftests/bpf/verifier/calls.c
@@ -374,6 +374,31 @@
.prog_type = BPF_PROG_TYPE_XDP,
.flags = F_NEEDS_EFFICIENT_UNALIGNED_ACCESS,
},
+{
+ "calls: ptr null check in subprog",
+ .insns = {
+ BPF_ST_MEM(BPF_DW, BPF_REG_10, -8, 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_EMIT_CALL(BPF_FUNC_map_lookup_elem),
+ BPF_MOV64_REG(BPF_REG_1, BPF_REG_0),
+ BPF_MOV64_REG(BPF_REG_6, BPF_REG_0),
+ BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 1, 0, 3),
+ BPF_JMP_IMM(BPF_JEQ, BPF_REG_0, 0, 1),
+ BPF_LDX_MEM(BPF_B, BPF_REG_0, BPF_REG_6, 0),
+ BPF_EXIT_INSN(),
+ BPF_MOV64_IMM(BPF_REG_0, 0),
+ BPF_JMP_IMM(BPF_JEQ, BPF_REG_1, 0, 1),
+ BPF_MOV64_IMM(BPF_REG_0, 1),
+ BPF_EXIT_INSN(),
+ },
+ .errstr_unpriv = "function calls to other bpf functions are allowed for root only",
+ .fixup_map_hash_48b = { 3 },
+ .result_unpriv = REJECT,
+ .result = ACCEPT,
+ .retval = 0,
+},
{
"calls: two calls with args",
.insns = {
--
2.17.1
