[PATCH 5.15 33/33] selftests/bpf: Add test for reg2btf_ids out of bounds access

[Greg Kroah-Hartman]

From: Kumar Kartikeya Dwivedi <memxor@xxxxxxxxx>

commit 13c6a37d409db9abc9c0bfc6d0a2f07bf0fff60e upstream.

This test tries to pass a PTR_TO_BTF_ID_OR_NULL to the release function,
which would trigger a out of bounds access without the fix in commit
45ce4b4f9009 ("bpf: Fix crash due to out of bounds access into reg2btf_ids.")
but after the fix, it should only index using base_type(reg->type),
which should be less than __BPF_REG_TYPE_MAX, and also not permit any
type flags to be set for the reg->type.

Signed-off-by: Kumar Kartikeya Dwivedi <memxor@xxxxxxxxx>
Signed-off-by: Alexei Starovoitov <ast@xxxxxxxxxx>
Link: https://lore.kernel.org/bpf/20220220023138.2224652-1-memxor@xxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 tools/testing/selftests/bpf/verifier/calls.c |   19 +++++++++++++++++++
 1 file changed, 19 insertions(+)

--- a/tools/testing/selftests/bpf/verifier/calls.c
+++ b/tools/testing/selftests/bpf/verifier/calls.c
@@ -108,6 +108,25 @@
 	.errstr = "R0 min value is outside of the allowed memory range",
 },
 {
+	"calls: trigger reg2btf_ids[reg->type] for reg->type > __BPF_REG_TYPE_MAX",
+	.insns = {
+	BPF_MOV64_REG(BPF_REG_1, BPF_REG_10),
+	BPF_ALU64_IMM(BPF_ADD, BPF_REG_1, -8),
+	BPF_ST_MEM(BPF_DW, BPF_REG_1, 0, 0),
+	BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, BPF_PSEUDO_KFUNC_CALL, 0, 0),
+	BPF_MOV64_REG(BPF_REG_1, BPF_REG_0),
+	BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, BPF_PSEUDO_KFUNC_CALL, 0, 0),
+	BPF_EXIT_INSN(),
+	},
+	.prog_type = BPF_PROG_TYPE_SCHED_CLS,
+	.result = REJECT,
+	.errstr = "arg#0 pointer type STRUCT prog_test_ref_kfunc must point",
+	.fixup_kfunc_btf_id = {
+		{ "bpf_kfunc_call_test_acquire", 3 },
+		{ "bpf_kfunc_call_test_release", 5 },
+	},
+},
+{
 	"calls: overlapping caller/callee",
 	.insns = {
 	BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 1, 0, 0),