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, 61 insertions, 0 deletions

diff --git a/drivers/pinctrl/mediatek/pinctrl-mt6397.c b/drivers/pinctrl/mediatek/pinctrl-mt6397.c
new file mode 100644
index 000000000..03d0f65d7
--- /dev/null
+++ b/drivers/pinctrl/mediatek/pinctrl-mt6397.c
@@ -0,0 +1,61 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (c) 2015 MediaTek Inc.
+ * Author: Hongzhou.Yang <hongzhou.yang@mediatek.com>
+ */
+
+#include <linux/init.h>
+#include <linux/platform_device.h>
+#include <linux/of.h>
+#include <linux/pinctrl/pinctrl.h>
+#include <linux/pinctrl/pinconf-generic.h>
+#include <linux/mfd/mt6397/core.h>
+
+#include "pinctrl-mtk-common.h"
+#include "pinctrl-mtk-mt6397.h"
+
+#define MT6397_PIN_REG_BASE  0xc000
+
+static const struct mtk_pinctrl_devdata mt6397_pinctrl_data = {
+	.pins = mtk_pins_mt6397,
+	.npins = ARRAY_SIZE(mtk_pins_mt6397),
+	.dir_offset = (MT6397_PIN_REG_BASE + 0x000),
+	.ies_offset = MTK_PINCTRL_NOT_SUPPORT,
+	.smt_offset = MTK_PINCTRL_NOT_SUPPORT,
+	.pullen_offset = (MT6397_PIN_REG_BASE + 0x020),
+	.pullsel_offset = (MT6397_PIN_REG_BASE + 0x040),
+	.dout_offset = (MT6397_PIN_REG_BASE + 0x080),
+	.din_offset = (MT6397_PIN_REG_BASE + 0x0a0),
+	.pinmux_offset = (MT6397_PIN_REG_BASE + 0x0c0),
+	.type1_start = 41,
+	.type1_end = 41,
+	.port_shf = 3,
+	.port_mask = 0x3,
+	.port_align = 2,
+	.mode_mask = 0xf,
+	.mode_per_reg = 5,
+	.mode_shf = 4,
+};
+
+static int mt6397_pinctrl_probe(struct platform_device *pdev)
+{
+	struct mt6397_chip *mt6397;
+
+	mt6397 = dev_get_drvdata(pdev->dev.parent);
+	return mtk_pctrl_init(pdev, &mt6397_pinctrl_data, mt6397->regmap);
+}
+
+static const struct of_device_id mt6397_pctrl_match[] = {
+	{ .compatible = "mediatek,mt6397-pinctrl", },
+	{ }
+};
+
+static struct platform_driver mtk_pinctrl_driver = {
+	.probe = mt6397_pinctrl_probe,
+	.driver = {
+		.name = "mediatek-mt6397-pinctrl",
+		.of_match_table = mt6397_pctrl_match,
+	},
+};
+
+builtin_platform_driver(mtk_pinctrl_driver);