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, 36 insertions, 0 deletions

diff --git a/fs/nilfs2/cpfile.h b/fs/nilfs2/cpfile.h
new file mode 100644
index 000000000..f5b1d5928
--- /dev/null
+++ b/fs/nilfs2/cpfile.h
@@ -0,0 +1,36 @@
+/* SPDX-License-Identifier: GPL-2.0+ */
+/*
+ * NILFS checkpoint file.
+ *
+ * Copyright (C) 2006-2008 Nippon Telegraph and Telephone Corporation.
+ *
+ * Written by Koji Sato.
+ */
+
+#ifndef _NILFS_CPFILE_H
+#define _NILFS_CPFILE_H
+
+#include <linux/fs.h>
+#include <linux/buffer_head.h>
+#include <linux/nilfs2_api.h>		/* nilfs_cpstat */
+#include <linux/nilfs2_ondisk.h>	/* nilfs_inode, nilfs_checkpoint */
+
+
+int nilfs_cpfile_read_checkpoint(struct inode *cpfile, __u64 cno,
+				 struct nilfs_root *root, struct inode *ifile);
+int nilfs_cpfile_create_checkpoint(struct inode *cpfile, __u64 cno);
+int nilfs_cpfile_finalize_checkpoint(struct inode *cpfile, __u64 cno,
+				     struct nilfs_root *root, __u64 blkinc,
+				     time64_t ctime, bool minor);
+int nilfs_cpfile_delete_checkpoints(struct inode *, __u64, __u64);
+int nilfs_cpfile_delete_checkpoint(struct inode *, __u64);
+int nilfs_cpfile_change_cpmode(struct inode *, __u64, int);
+int nilfs_cpfile_is_snapshot(struct inode *, __u64);
+int nilfs_cpfile_get_stat(struct inode *, struct nilfs_cpstat *);
+ssize_t nilfs_cpfile_get_cpinfo(struct inode *, __u64 *, int, void *,
+				unsigned int, size_t);
+
+int nilfs_cpfile_read(struct super_block *sb, size_t cpsize,
+		      struct nilfs_inode *raw_inode, struct inode **inodep);
+
+#endif	/* _NILFS_CPFILE_H */