selftests/bpf: Reject graph kptr use after RCU unlockgrafted

Add a sleepable verifier test that loads a graph-node local kptr in an
explicit RCU read-side critical section, then passes its node to
bpf_rbtree_remove() after the section ends.

Before the verifier fix, the stale NON_OWN_REF flag makes the node look like
a live borrowed reference and the program is accepted. After the fix, the
pointer is demoted without NON_OWN_REF and the graph kfunc argument is
rejected.

Also exercise a graph kptr loaded while a spin lock provides implicit RCU
protection. The pointer must be invalidated when the lock is released, which
guards the required ordering between non-owning-reference invalidation and
RCU demotion.

Update the existing fault-protected load test state description. The
post-unlock pointer no longer carries NON_OWN_REF, but remains readable
because the load is rewritten to use BPF_PROBE_MEM.

Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20260904084325.52250-7-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

1 files changed, 94 insertions, 0 deletions

diff --git a/drivers/hid/hid-roccat-common.h b/drivers/hid/hid-roccat-common.h
new file mode 100644
index 000000000..e931d0b48
--- /dev/null
+++ b/drivers/hid/hid-roccat-common.h
@@ -0,0 +1,94 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+#ifndef __HID_ROCCAT_COMMON_H
+#define __HID_ROCCAT_COMMON_H
+
+/*
+ * Copyright (c) 2011 Stefan Achatz <erazor_de@users.sourceforge.net>
+ */
+
+/*
+ */
+
+#include <linux/usb.h>
+#include <linux/types.h>
+
+enum roccat_common2_commands {
+	ROCCAT_COMMON_COMMAND_CONTROL = 0x4,
+};
+
+struct roccat_common2_control {
+	uint8_t command;
+	uint8_t value;
+	uint8_t request; /* always 0 on requesting write check */
+} __packed;
+
+int roccat_common2_receive(struct usb_device *usb_dev, uint report_id,
+		void *data, uint size);
+int roccat_common2_send(struct usb_device *usb_dev, uint report_id,
+		void const *data, uint size);
+int roccat_common2_send_with_status(struct usb_device *usb_dev,
+		uint command, void const *buf, uint size);
+
+struct roccat_common2_device {
+	int roccat_claimed;
+	int chrdev_minor;
+	struct mutex lock;
+};
+
+int roccat_common2_device_init_struct(struct usb_device *usb_dev,
+		struct roccat_common2_device *dev);
+ssize_t roccat_common2_sysfs_read(struct file *fp, struct kobject *kobj,
+		char *buf, loff_t off, size_t count,
+		size_t real_size, uint command);
+ssize_t roccat_common2_sysfs_write(struct file *fp, struct kobject *kobj,
+		void const *buf, loff_t off, size_t count,
+		size_t real_size, uint command);
+
+#define ROCCAT_COMMON2_SYSFS_W(thingy, COMMAND, SIZE) \
+static ssize_t roccat_common2_sysfs_write_ ## thingy(struct file *fp, \
+		struct kobject *kobj, const struct bin_attribute *attr, \
+		char *buf, loff_t off, size_t count) \
+{ \
+	return roccat_common2_sysfs_write(fp, kobj, buf, off, count, \
+			SIZE, COMMAND); \
+}
+
+#define ROCCAT_COMMON2_SYSFS_R(thingy, COMMAND, SIZE) \
+static ssize_t roccat_common2_sysfs_read_ ## thingy(struct file *fp, \
+		struct kobject *kobj, const struct bin_attribute *attr, \
+		char *buf, loff_t off, size_t count) \
+{ \
+	return roccat_common2_sysfs_read(fp, kobj, buf, off, count, \
+			SIZE, COMMAND); \
+}
+
+#define ROCCAT_COMMON2_SYSFS_RW(thingy, COMMAND, SIZE) \
+ROCCAT_COMMON2_SYSFS_W(thingy, COMMAND, SIZE) \
+ROCCAT_COMMON2_SYSFS_R(thingy, COMMAND, SIZE)
+
+#define ROCCAT_COMMON2_BIN_ATTRIBUTE_RW(thingy, COMMAND, SIZE) \
+ROCCAT_COMMON2_SYSFS_RW(thingy, COMMAND, SIZE); \
+static const struct bin_attribute bin_attr_ ## thingy = { \
+	.attr = { .name = #thingy, .mode = 0660 }, \
+	.size = SIZE, \
+	.read = roccat_common2_sysfs_read_ ## thingy, \
+	.write = roccat_common2_sysfs_write_ ## thingy \
+}
+
+#define ROCCAT_COMMON2_BIN_ATTRIBUTE_R(thingy, COMMAND, SIZE) \
+ROCCAT_COMMON2_SYSFS_R(thingy, COMMAND, SIZE); \
+static const struct bin_attribute bin_attr_ ## thingy = { \
+	.attr = { .name = #thingy, .mode = 0440 }, \
+	.size = SIZE, \
+	.read = roccat_common2_sysfs_read_ ## thingy, \
+}
+
+#define ROCCAT_COMMON2_BIN_ATTRIBUTE_W(thingy, COMMAND, SIZE) \
+ROCCAT_COMMON2_SYSFS_W(thingy, COMMAND, SIZE); \
+static const struct bin_attribute bin_attr_ ## thingy = { \
+	.attr = { .name = #thingy, .mode = 0220 }, \
+	.size = SIZE, \
+	.write = roccat_common2_sysfs_write_ ## thingy \
+}
+
+#endif