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, 63 insertions, 0 deletions

diff --git a/fs/ntfs/debug.h b/fs/ntfs/debug.h
new file mode 100644
index 000000000..d8831d492
--- /dev/null
+++ b/fs/ntfs/debug.h
@@ -0,0 +1,63 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * NTFS kernel debug support.
+ *
+ * Copyright (c) 2001-2004 Anton Altaparmakov
+ */
+
+#ifndef _LINUX_NTFS_DEBUG_H
+#define _LINUX_NTFS_DEBUG_H
+
+#include <linux/fs.h>
+
+#include "runlist.h"
+
+#ifdef DEBUG
+
+extern int debug_msgs;
+
+extern __printf(4, 5)
+void __ntfs_debug(const char *file, int line, const char *function,
+		  const char *format, ...);
+/*
+ * ntfs_debug - write a debug level message to syslog
+ * @f:		a printf format string containing the message
+ * @...:	the variables to substitute into @f
+ *
+ * ntfs_debug() writes a DEBUG level message to the syslog but only if the
+ * driver was compiled with -DDEBUG. Otherwise, the call turns into a NOP.
+ */
+#define ntfs_debug(f, a...)						\
+	__ntfs_debug(__FILE__, __LINE__, __func__, f, ##a)
+
+void ntfs_debug_dump_runlist(const struct runlist_element *rl);
+
+#else	/* !DEBUG */
+
+#define ntfs_debug(fmt, ...)						\
+do {									\
+	if (0)								\
+		no_printk(fmt, ##__VA_ARGS__);				\
+} while (0)
+
+#define ntfs_debug_dump_runlist(rl)					\
+do {									\
+	if (0)								\
+		(void)rl;						\
+} while (0)
+
+#endif	/* !DEBUG */
+
+extern  __printf(3, 4)
+void __ntfs_warning(const char *function, const struct super_block *sb,
+		    const char *fmt, ...);
+#define ntfs_warning(sb, f, a...)	__ntfs_warning(__func__, sb, f, ##a)
+
+extern  __printf(3, 4)
+void __ntfs_error(const char *function, struct super_block *sb,
+		  const char *fmt, ...);
+#define ntfs_error(sb, f, a...)		__ntfs_error(__func__, sb, f, ##a)
+
+void ntfs_handle_error(struct super_block *sb);
+
+#endif /* _LINUX_NTFS_DEBUG_H */