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, 45 insertions, 0 deletions

diff --git a/fs/nilfs2/ifile.h b/fs/nilfs2/ifile.h
new file mode 100644
index 000000000..d38a46f5a
--- /dev/null
+++ b/fs/nilfs2/ifile.h
@@ -0,0 +1,45 @@
+/* SPDX-License-Identifier: GPL-2.0+ */
+/*
+ * NILFS inode file
+ *
+ * Copyright (C) 2006-2008 Nippon Telegraph and Telephone Corporation.
+ *
+ * Written by Amagai Yoshiji.
+ * Revised by Ryusuke Konishi.
+ *
+ */
+
+#ifndef _NILFS_IFILE_H
+#define _NILFS_IFILE_H
+
+#include <linux/fs.h>
+#include <linux/buffer_head.h>
+#include "mdt.h"
+#include "alloc.h"
+
+
+static inline struct nilfs_inode *
+nilfs_ifile_map_inode(struct inode *ifile, u64 ino, struct buffer_head *ibh)
+{
+	size_t __offset_in_folio = nilfs_palloc_entry_offset(ifile, ino, ibh);
+
+	return kmap_local_folio(ibh->b_folio, __offset_in_folio);
+}
+
+static inline void nilfs_ifile_unmap_inode(struct nilfs_inode *raw_inode)
+{
+	kunmap_local(raw_inode);
+}
+
+int nilfs_ifile_create_inode(struct inode *ifile, u64 *out_ino,
+			struct buffer_head **out_bh);
+int nilfs_ifile_delete_inode(struct inode *ifile, u64 ino);
+int nilfs_ifile_get_inode_block(struct inode *ifile, u64 ino,
+				struct buffer_head **out_bh);
+
+int nilfs_ifile_count_free_inodes(struct inode *, u64 *, u64 *);
+
+int nilfs_ifile_read(struct super_block *sb, struct nilfs_root *root,
+		     __u64 cno, size_t inode_size);
+
+#endif	/* _NILFS_IFILE_H */