test/regbuf-clone: test dummy ubuf cloning

The 6.12-rc kernels had a bug where the cloning would attempt to grab
a reference to a dummy ubuf that was assigned, which would crash the
kernel. Add a test case for that.

Signed-off-by: Jens Axboe <[email protected]>

test/regbuf-clone.c

@@ -15,6 +15,8 @@
 #define NR_VECS		64
 #define BUF_SIZE	8192
 
+static int no_buf_clone;
+
 static int test(int reg_src, int reg_dst)
 {
 	struct iovec vecs[NR_VECS];
@@ -54,6 +56,7 @@ static int test(int reg_src, int reg_dst)
 	ret = io_uring_clone_buffers(&dst, &src);
 	if (ret == -EINVAL) {
 		/* no buffer copy support */
+		no_buf_clone = true;
 		return T_EXIT_SKIP;
 	} else if (ret != -ENXIO) {
 		fprintf(stderr, "empty copy: %d\n", ret);
@@ -144,6 +147,53 @@ static int test(int reg_src, int reg_dst)
 	return T_EXIT_PASS;
 }
 
+static int test_dummy(void)
+{
+	struct iovec vec = { };
+	struct io_uring src, dst;
+	int ret;
+
+	ret = io_uring_queue_init(1, &src, 0);
+	if (ret) {
+		fprintf(stderr, "ring_init: %d\n", ret);
+		return T_EXIT_FAIL;
+	}
+	ret = io_uring_queue_init(1, &dst, 0);
+	if (ret) {
+		fprintf(stderr, "ring_init: %d\n", ret);
+		return T_EXIT_FAIL;
+	}
+
+	ret = io_uring_register_buffers(&src, &vec, 1);
+	if (ret < 0) {
+		fprintf(stderr, "failed to register dummy buffer: %d\n", ret);
+		return T_EXIT_FAIL;
+	}
+
+	ret = io_uring_clone_buffers(&dst, &src);
+	if (ret) {
+		fprintf(stderr, "clone dummy buf: %d\n", ret);
+		return T_EXIT_FAIL;
+	}
+
+	ret = io_uring_unregister_buffers(&src);
+	if (ret) {
+		fprintf(stderr, "rsc unregister buffers: %d\n", ret);
+		return T_EXIT_FAIL;
+	}
+
+	ret = io_uring_unregister_buffers(&dst);
+	if (ret) {
+		fprintf(stderr, "dst unregister buffers: %d\n", ret);
+		return T_EXIT_FAIL;
+	}
+
+	io_uring_queue_exit(&src);
+	io_uring_queue_exit(&dst);
+
+	return T_EXIT_PASS;
+}
+
 int main(int argc, char *argv[])
 {
 	int ret;
@@ -158,6 +208,8 @@ int main(int argc, char *argv[])
 		fprintf(stderr, "test 0 0 failed\n");
 		return T_EXIT_FAIL;
 	}
+	if (no_buf_clone)
+		return T_EXIT_SKIP;
 
 	ret = test(0, 1);
 	if (ret == T_EXIT_SKIP) {
@@ -183,5 +235,13 @@ int main(int argc, char *argv[])
 		return T_EXIT_FAIL;
 	}
 
+	ret = test_dummy();
+	if (ret == T_EXIT_SKIP) {
+		return T_EXIT_SKIP;
+	} else if (ret != T_EXIT_PASS) {
+		fprintf(stderr, "test_dummy failed\n");
+		return T_EXIT_FAIL;
+	}
+
 	return T_EXIT_PASS;
 }