From 6668ed271eaefaa63e686bdfbedaeb7b8e492722 Mon Sep 17 00:00:00 2001 From: Kumar Kartikeya Dwivedi Date: Fri, 4 Sep 2026 10:43:19 +0200 Subject: selftests/bpf: Reject graph kptr use after RCU unlock 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 Link: https://lore.kernel.org/r/20260904084325.52250-7-memxor@gmail.com Signed-off-by: Alexei Starovoitov --- drivers/hid/hid-picolcd_lcd.c | 88 +++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 88 insertions(+) create mode 100644 drivers/hid/hid-picolcd_lcd.c (limited to 'drivers/hid/hid-picolcd_lcd.c') diff --git a/drivers/hid/hid-picolcd_lcd.c b/drivers/hid/hid-picolcd_lcd.c new file mode 100644 index 000000000..318f19eac --- /dev/null +++ b/drivers/hid/hid-picolcd_lcd.c @@ -0,0 +1,88 @@ +// SPDX-License-Identifier: GPL-2.0-only +/*************************************************************************** + * Copyright (C) 2010-2012 by Bruno Prémont * + * * + * Based on Logitech G13 driver (v0.4) * + * Copyright (C) 2009 by Rick L. Vinyard, Jr. * + * * + ***************************************************************************/ + +#include + +#include +#include + +#include "hid-picolcd.h" + +/* + * lcd class device + */ +static int picolcd_get_contrast(struct lcd_device *ldev) +{ + struct picolcd_data *data = lcd_get_data(ldev); + return data->lcd_contrast; +} + +static int picolcd_set_contrast(struct lcd_device *ldev, int contrast) +{ + struct picolcd_data *data = lcd_get_data(ldev); + struct hid_report *report = picolcd_out_report(REPORT_CONTRAST, data->hdev); + unsigned long flags; + + if (!report || report->maxfield != 1 || report->field[0]->report_count != 1) + return -ENODEV; + + data->lcd_contrast = contrast & 0x0ff; + spin_lock_irqsave(&data->lock, flags); + hid_set_field(report->field[0], 0, data->lcd_contrast); + if (!(data->status & PICOLCD_FAILED)) + hid_hw_request(data->hdev, report, HID_REQ_SET_REPORT); + spin_unlock_irqrestore(&data->lock, flags); + return 0; +} + +static const struct lcd_ops picolcd_lcdops = { + .get_contrast = picolcd_get_contrast, + .set_contrast = picolcd_set_contrast, +}; + +int picolcd_init_lcd(struct picolcd_data *data, struct hid_report *report) +{ + struct device *dev = &data->hdev->dev; + struct lcd_device *ldev; + + if (!report) + return -ENODEV; + if (report->maxfield != 1 || report->field[0]->report_count != 1 || + report->field[0]->report_size != 8) { + dev_err(dev, "unsupported CONTRAST report"); + return -EINVAL; + } + + ldev = lcd_device_register(dev_name(dev), dev, data, &picolcd_lcdops); + if (IS_ERR(ldev)) { + dev_err(dev, "failed to register LCD\n"); + return PTR_ERR(ldev); + } + ldev->props.max_contrast = 0x0ff; + data->lcd_contrast = 0xe5; + data->lcd = ldev; + picolcd_set_contrast(ldev, 0xe5); + return 0; +} + +void picolcd_exit_lcd(struct picolcd_data *data) +{ + struct lcd_device *ldev = data->lcd; + + data->lcd = NULL; + lcd_device_unregister(ldev); +} + +int picolcd_resume_lcd(struct picolcd_data *data) +{ + if (!data->lcd) + return 0; + return picolcd_set_contrast(data->lcd, data->lcd_contrast); +} + -- cgit v1.3.1