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, 92 insertions, 0 deletions

diff --git a/include/uapi/mtd/inftl-user.h b/include/uapi/mtd/inftl-user.h
new file mode 100644
index 000000000..8d5044e32
--- /dev/null
+++ b/include/uapi/mtd/inftl-user.h
@@ -0,0 +1,92 @@
+/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
+/*
+ * Parts of INFTL headers shared with userspace
+ *
+ */
+
+#ifndef __MTD_INFTL_USER_H__
+#define __MTD_INFTL_USER_H__
+
+#include <linux/types.h>
+
+#define	OSAK_VERSION	0x5120
+#define	PERCENTUSED	98
+
+#define	SECTORSIZE	512
+
+/* Block Control Information */
+
+struct inftl_bci {
+	__u8 ECCsig[6];
+	__u8 Status;
+	__u8 Status1;
+} __attribute__((packed));
+
+struct inftl_unithead1 {
+	__u16 virtualUnitNo;
+	__u16 prevUnitNo;
+	__u8 ANAC;
+	__u8 NACs;
+	__u8 parityPerField;
+	__u8 discarded;
+} __attribute__((packed));
+
+struct inftl_unithead2 {
+	__u8 parityPerField;
+	__u8 ANAC;
+	__u16 prevUnitNo;
+	__u16 virtualUnitNo;
+	__u8 NACs;
+	__u8 discarded;
+} __attribute__((packed));
+
+struct inftl_unittail {
+	__u8 Reserved[4];
+	__u16 EraseMark;
+	__u16 EraseMark1;
+} __attribute__((packed));
+
+union inftl_uci {
+	struct inftl_unithead1 a;
+	struct inftl_unithead2 b;
+	struct inftl_unittail c;
+};
+
+struct inftl_oob {
+	struct inftl_bci b;
+	union inftl_uci u;
+};
+
+
+/* INFTL Media Header */
+
+struct INFTLPartition {
+	__u32 virtualUnits;
+	__u32 firstUnit;
+	__u32 lastUnit;
+	__u32 flags;
+	__u32 spareUnits;
+	__u32 Reserved0;
+	__u32 Reserved1;
+} __attribute__((packed));
+
+struct INFTLMediaHeader {
+	char bootRecordID[8];
+	__u32 NoOfBootImageBlocks;
+	__u32 NoOfBinaryPartitions;
+	__u32 NoOfBDTLPartitions;
+	__u32 BlockMultiplierBits;
+	__u32 FormatFlags;
+	__u32 OsakVersion;
+	__u32 PercentUsed;
+	struct INFTLPartition Partitions[4];
+} __attribute__((packed));
+
+/* Partition flag types */
+#define	INFTL_BINARY	0x20000000
+#define	INFTL_BDTL	0x40000000
+#define	INFTL_LAST	0x80000000
+
+#endif /* __MTD_INFTL_USER_H__ */
+
+