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, 101 insertions, 0 deletions

diff --git a/drivers/dma/dw/internal.h b/drivers/dma/dw/internal.h
new file mode 100644
index 000000000..f1bd06a20
--- /dev/null
+++ b/drivers/dma/dw/internal.h
@@ -0,0 +1,101 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Driver for the Synopsys DesignWare DMA Controller
+ *
+ * Copyright (C) 2013 Intel Corporation
+ */
+
+#ifndef _DMA_DW_INTERNAL_H
+#define _DMA_DW_INTERNAL_H
+
+#include <linux/dma/dw.h>
+
+#include "regs.h"
+
+int do_dma_probe(struct dw_dma_chip *chip);
+int do_dma_remove(struct dw_dma_chip *chip);
+
+void do_dw_dma_on(struct dw_dma *dw);
+void do_dw_dma_off(struct dw_dma *dw);
+
+int do_dw_dma_disable(struct dw_dma_chip *chip);
+int do_dw_dma_enable(struct dw_dma_chip *chip);
+
+extern bool dw_dma_filter(struct dma_chan *chan, void *param);
+
+#ifdef CONFIG_ACPI
+void dw_dma_acpi_controller_register(struct dw_dma *dw);
+void dw_dma_acpi_controller_free(struct dw_dma *dw);
+#else /* !CONFIG_ACPI */
+static inline void dw_dma_acpi_controller_register(struct dw_dma *dw) {}
+static inline void dw_dma_acpi_controller_free(struct dw_dma *dw) {}
+#endif /* !CONFIG_ACPI */
+
+struct platform_device;
+
+#ifdef CONFIG_OF
+struct dw_dma_platform_data *dw_dma_parse_dt(struct platform_device *pdev);
+void dw_dma_of_controller_register(struct dw_dma *dw);
+void dw_dma_of_controller_free(struct dw_dma *dw);
+#else
+static inline struct dw_dma_platform_data *dw_dma_parse_dt(struct platform_device *pdev)
+{
+	return NULL;
+}
+static inline void dw_dma_of_controller_register(struct dw_dma *dw) {}
+static inline void dw_dma_of_controller_free(struct dw_dma *dw) {}
+#endif
+
+struct dw_dma_chip_pdata {
+	const struct dw_dma_platform_data *pdata;
+	int (*probe)(struct dw_dma_chip *chip);
+	int (*remove)(struct dw_dma_chip *chip);
+	struct dw_dma_chip *chip;
+	u8 m_master;
+	u8 p_master;
+};
+
+static __maybe_unused const struct dw_dma_chip_pdata dw_dma_chip_pdata = {
+	.probe = dw_dma_probe,
+	.remove = dw_dma_remove,
+	.m_master = 0,
+	.p_master = 1,
+};
+
+static const struct dw_dma_platform_data idma32_pdata = {
+	.nr_channels = 8,
+	.chan_allocation_order = CHAN_ALLOCATION_ASCENDING,
+	.chan_priority = CHAN_PRIORITY_ASCENDING,
+	.block_size = 131071,
+	.nr_masters = 1,
+	.data_width = {4},
+	.multi_block = {1, 1, 1, 1, 1, 1, 1, 1},
+};
+
+static __maybe_unused const struct dw_dma_chip_pdata idma32_chip_pdata = {
+	.pdata = &idma32_pdata,
+	.probe = idma32_dma_probe,
+	.remove = idma32_dma_remove,
+	.m_master = 0,
+	.p_master = 0,
+};
+
+static const struct dw_dma_platform_data xbar_pdata = {
+	.nr_channels = 8,
+	.chan_allocation_order = CHAN_ALLOCATION_ASCENDING,
+	.chan_priority = CHAN_PRIORITY_ASCENDING,
+	.block_size = 131071,
+	.nr_masters = 1,
+	.data_width = {4},
+	.quirks = DW_DMA_QUIRK_XBAR_PRESENT,
+};
+
+static __maybe_unused const struct dw_dma_chip_pdata xbar_chip_pdata = {
+	.pdata = &xbar_pdata,
+	.probe = idma32_dma_probe,
+	.remove = idma32_dma_remove,
+	.m_master = 0,
+	.p_master = 0,
+};
+
+#endif /* _DMA_DW_INTERNAL_H */