bpf: mark a NULL kfunc argument precisegrafted

check_kfunc_arg() allows bpf_register_is_null() for nullable arguments
w/o marking the underlying scalar register precise. Hence a checkpoint
created on such a path would prune against arbitrary scalar value.

Fixes: 3bda08b63670 ("bpf: Allow NULL buffers in bpf_dynptr_slice(_rw)")
Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20260904-register-is-null-precise-fixes-v1-5-0f5a360ff15d@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

1 files changed, 64 insertions, 0 deletions

diff --git a/drivers/spmi/spmi-devres.c b/drivers/spmi/spmi-devres.c
new file mode 100644
index 000000000..62c4b3f24
--- /dev/null
+++ b/drivers/spmi/spmi-devres.c
@@ -0,0 +1,64 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright 2023 Google LLC.
+ */
+
+#include <linux/device.h>
+#include <linux/spmi.h>
+
+static void devm_spmi_controller_release(struct device *parent, void *res)
+{
+	spmi_controller_put(*(struct spmi_controller **)res);
+}
+
+struct spmi_controller *devm_spmi_controller_alloc(struct device *parent, size_t size)
+{
+	struct spmi_controller **ptr, *ctrl;
+
+	ptr = devres_alloc(devm_spmi_controller_release, sizeof(*ptr), GFP_KERNEL);
+	if (!ptr)
+		return ERR_PTR(-ENOMEM);
+
+	ctrl = spmi_controller_alloc(parent, size);
+	if (IS_ERR(ctrl)) {
+		devres_free(ptr);
+		return ctrl;
+	}
+
+	*ptr = ctrl;
+	devres_add(parent, ptr);
+
+	return ctrl;
+}
+EXPORT_SYMBOL_GPL(devm_spmi_controller_alloc);
+
+static void devm_spmi_controller_remove(struct device *parent, void *res)
+{
+	spmi_controller_remove(*(struct spmi_controller **)res);
+}
+
+int devm_spmi_controller_add(struct device *parent, struct spmi_controller *ctrl)
+{
+	struct spmi_controller **ptr;
+	int ret;
+
+	ptr = devres_alloc(devm_spmi_controller_remove, sizeof(*ptr), GFP_KERNEL);
+	if (!ptr)
+		return -ENOMEM;
+
+	ret = spmi_controller_add(ctrl);
+	if (ret) {
+		devres_free(ptr);
+		return ret;
+	}
+
+	*ptr = ctrl;
+	devres_add(parent, ptr);
+
+	return 0;
+
+}
+EXPORT_SYMBOL_GPL(devm_spmi_controller_add);
+
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("SPMI devres helpers");