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, 87 insertions, 0 deletions

diff --git a/drivers/accessibility/speakup/fakekey.c b/drivers/accessibility/speakup/fakekey.c
new file mode 100644
index 000000000..868c47b2a
--- /dev/null
+++ b/drivers/accessibility/speakup/fakekey.c
@@ -0,0 +1,87 @@
+// SPDX-License-Identifier: GPL-2.0+
+/* fakekey.c
+ * Functions for simulating key presses.
+ *
+ * Copyright (C) 2010 the Speakup Team
+ */
+#include <linux/types.h>
+#include <linux/slab.h>
+#include <linux/preempt.h>
+#include <linux/percpu.h>
+#include <linux/input.h>
+
+#include "speakup.h"
+
+#define PRESSED 1
+#define RELEASED 0
+
+static DEFINE_PER_CPU(int, reporting_keystroke);
+
+static struct input_dev *virt_keyboard;
+
+int speakup_add_virtual_keyboard(void)
+{
+	int err;
+
+	virt_keyboard = input_allocate_device();
+
+	if (!virt_keyboard)
+		return -ENOMEM;
+
+	virt_keyboard->name = "Speakup";
+	virt_keyboard->id.bustype = BUS_VIRTUAL;
+	virt_keyboard->phys = "speakup/input0";
+	virt_keyboard->dev.parent = NULL;
+
+	__set_bit(EV_KEY, virt_keyboard->evbit);
+	__set_bit(KEY_DOWN, virt_keyboard->keybit);
+
+	err = input_register_device(virt_keyboard);
+	if (err) {
+		input_free_device(virt_keyboard);
+		virt_keyboard = NULL;
+	}
+
+	return err;
+}
+
+void speakup_remove_virtual_keyboard(void)
+{
+	if (virt_keyboard) {
+		input_unregister_device(virt_keyboard);
+		virt_keyboard = NULL;
+	}
+}
+
+/*
+ * Send a simulated down-arrow to the application.
+ */
+void speakup_fake_down_arrow(void)
+{
+	unsigned long flags;
+
+	/* disable keyboard interrupts */
+	local_irq_save(flags);
+	/* don't change CPU */
+	preempt_disable();
+
+	__this_cpu_write(reporting_keystroke, true);
+	input_report_key(virt_keyboard, KEY_DOWN, PRESSED);
+	input_report_key(virt_keyboard, KEY_DOWN, RELEASED);
+	input_sync(virt_keyboard);
+	__this_cpu_write(reporting_keystroke, false);
+
+	/* reenable preemption */
+	preempt_enable();
+	/* reenable keyboard interrupts */
+	local_irq_restore(flags);
+}
+
+/*
+ * Are we handling a simulated key press on the current CPU?
+ * Returns a boolean.
+ */
+bool speakup_fake_key_pressed(void)
+{
+	return this_cpu_read(reporting_keystroke);
+}