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, 31 insertions, 0 deletions

diff --git a/drivers/leds/trigger/ledtrig-default-on.c b/drivers/leds/trigger/ledtrig-default-on.c
new file mode 100644
index 000000000..8678e64a5
--- /dev/null
+++ b/drivers/leds/trigger/ledtrig-default-on.c
@@ -0,0 +1,31 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * LED Kernel Default ON Trigger
+ *
+ * Copyright 2008 Nick Forbes <nick.forbes@incepta.com>
+ *
+ * Based on Richard Purdie's ledtrig-timer.c.
+ */
+
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/leds.h>
+#include "../leds.h"
+
+static int defon_trig_activate(struct led_classdev *led_cdev)
+{
+	led_set_brightness_nosleep(led_cdev, led_cdev->max_brightness);
+	return 0;
+}
+
+static struct led_trigger defon_led_trigger = {
+	.name     = "default-on",
+	.activate = defon_trig_activate,
+};
+module_led_trigger(defon_led_trigger);
+
+MODULE_AUTHOR("Nick Forbes <nick.forbes@incepta.com>");
+MODULE_DESCRIPTION("Default-ON LED trigger");
+MODULE_LICENSE("GPL v2");
+MODULE_ALIAS("ledtrig:default-on");