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/video/backlight/rave-sp-backlight.c | 89 +++++++++++++++++++++++++++++ 1 file changed, 89 insertions(+) create mode 100644 drivers/video/backlight/rave-sp-backlight.c (limited to 'drivers/video/backlight/rave-sp-backlight.c') diff --git a/drivers/video/backlight/rave-sp-backlight.c b/drivers/video/backlight/rave-sp-backlight.c new file mode 100644 index 000000000..b7528ef02 --- /dev/null +++ b/drivers/video/backlight/rave-sp-backlight.c @@ -0,0 +1,89 @@ +// SPDX-License-Identifier: GPL-2.0+ + +/* + * LCD Backlight driver for RAVE SP + * + * Copyright (C) 2018 Zodiac Inflight Innovations + * + */ + +#include +#include +#include +#include +#include +#include + +#define RAVE_SP_BACKLIGHT_LCD_EN BIT(7) + +static int rave_sp_backlight_update_status(struct backlight_device *bd) +{ + const struct backlight_properties *p = &bd->props; + const u8 intensity = + (p->power == BACKLIGHT_POWER_ON) ? p->brightness : 0; + struct rave_sp *sp = dev_get_drvdata(&bd->dev); + u8 cmd[] = { + [0] = RAVE_SP_CMD_SET_BACKLIGHT, + [1] = 0, + [2] = intensity ? RAVE_SP_BACKLIGHT_LCD_EN | intensity : 0, + [3] = 0, + [4] = 0, + }; + + return rave_sp_exec(sp, cmd, sizeof(cmd), NULL, 0); +} + +static const struct backlight_ops rave_sp_backlight_ops = { + .options = BL_CORE_SUSPENDRESUME, + .update_status = rave_sp_backlight_update_status, +}; + +static struct backlight_properties rave_sp_backlight_props = { + .type = BACKLIGHT_PLATFORM, + .max_brightness = 100, + .brightness = 50, +}; + +static int rave_sp_backlight_probe(struct platform_device *pdev) +{ + struct device *dev = &pdev->dev; + struct backlight_device *bd; + + bd = devm_backlight_device_register(dev, pdev->name, dev, + dev_get_drvdata(dev->parent), + &rave_sp_backlight_ops, + &rave_sp_backlight_props); + if (IS_ERR(bd)) + return PTR_ERR(bd); + + /* + * If there is a phandle pointing to the device node we can + * assume that another device will manage the status changes. + * If not we make sure the backlight is in a consistent state. + */ + if (!dev->of_node->phandle) + backlight_update_status(bd); + + return 0; +} + +static const struct of_device_id rave_sp_backlight_of_match[] = { + { .compatible = "zii,rave-sp-backlight" }, + {} +}; + +static struct platform_driver rave_sp_backlight_driver = { + .probe = rave_sp_backlight_probe, + .driver = { + .name = KBUILD_MODNAME, + .of_match_table = rave_sp_backlight_of_match, + }, +}; +module_platform_driver(rave_sp_backlight_driver); + +MODULE_DEVICE_TABLE(of, rave_sp_backlight_of_match); +MODULE_LICENSE("GPL"); +MODULE_AUTHOR("Andrey Vostrikov "); +MODULE_AUTHOR("Nikita Yushchenko "); +MODULE_AUTHOR("Andrey Smirnov "); +MODULE_DESCRIPTION("RAVE SP Backlight driver"); -- cgit v1.3.1