First test that we allow overwriting dynptr slots and reinitializing
them. Next, test that MEM_UNINIT doesn't allow writing dynptr stack
slots.
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@xxxxxxxxx>
---
.../testing/selftests/bpf/progs/dynptr_fail.c | 62 +++++++++++++++++++
1 file changed, 62 insertions(+)
diff --git a/tools/testing/selftests/bpf/progs/dynptr_fail.c b/tools/testing/selftests/bpf/progs/dynptr_fail.c
index 32df3647b794..73ae93dedaba 100644
--- a/tools/testing/selftests/bpf/progs/dynptr_fail.c
+++ b/tools/testing/selftests/bpf/progs/dynptr_fail.c
@@ -653,3 +653,65 @@ int dynptr_from_mem_invalid_api(void *ctx)
return 0;
}
+
+SEC("?raw_tp")
+__success
+int dynptr_overwrite_unref(void *ctx)
+{
+ struct bpf_dynptr ptr;
+
+ get_map_val_dynptr(&ptr);
+ get_map_val_dynptr(&ptr);
+ get_map_val_dynptr(&ptr);
+
+ return 0;
+}
+
+SEC("?raw_tp")
+__failure __msg("Unreleased reference")
+int dynptr_overwrite_ref(void *ctx)
+{
+ struct bpf_dynptr ptr;
+
+ bpf_ringbuf_reserve_dynptr(&ringbuf, 64, 0, &ptr);
+ if (get_map_val_dynptr(&ptr))
+ bpf_ringbuf_discard_dynptr(&ptr, 0);
+ return 0;
+}
+
+/* Reject writes to dynptr slot from bpf_dynptr_read */
+SEC("?raw_tp")
+__failure __msg("potential write to dynptr at off=-16")
+int dynptr_read_into_slot(void *ctx)
+{
+ union {
+ struct {
+ char _pad[48];
+ struct bpf_dynptr ptr;
+ };
+ char buf[64];
+ } data;
+
+ bpf_ringbuf_reserve_dynptr(&ringbuf, 64, 0, &data.ptr);
+ /* this should fail */
+ bpf_dynptr_read(data.buf, sizeof(data.buf), &data.ptr, 0, 0);
+
+ return 0;
+}
+
+/* Reject writes to dynptr slot for uninit arg */
+SEC("?raw_tp")
+__failure __msg("potential write to dynptr at off=-16")
+int uninit_write_into_slot(void *ctx)
+{
+ struct {
+ char buf[64];
+ struct bpf_dynptr ptr;
+ } data;
+
+ bpf_ringbuf_reserve_dynptr(&ringbuf, 80, 0, &data.ptr);
+ /* this should fail */
+ bpf_get_current_comm(data.buf, 80);
+
+ return 0;
+}
--
2.39.0
