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, 41 insertions, 0 deletions

diff --git a/fs/smb/server/unicode.h b/fs/smb/server/unicode.h
new file mode 100644
index 000000000..28c7c736f
--- /dev/null
+++ b/fs/smb/server/unicode.h
@@ -0,0 +1,41 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * Some of the source code in this file came from fs/cifs/cifs_unicode.c
+ * cifs_unicode:  Unicode kernel case support
+ *
+ * Function:
+ *     Convert a unicode character to upper or lower case using
+ *     compressed tables.
+ *
+ *   Copyright (c) International Business Machines  Corp., 2000,2009
+ *
+ *
+ * Notes:
+ *     These APIs are based on the C library functions.  The semantics
+ *     should match the C functions but with expanded size operands.
+ *
+ *     The upper/lower functions are based on a table created by mkupr.
+ *     This is a compressed table of upper and lower case conversion.
+ *
+ */
+#ifndef _SMB_UNICODE_H
+#define _SMB_UNICODE_H
+
+#include <asm/byteorder.h>
+#include <linux/types.h>
+#include <linux/nls.h>
+#include <linux/unicode.h>
+#include "../../nls/nls_ucs2_utils.h"
+
+#ifdef __KERNEL__
+int smb_strtoUTF16(__le16 *to, const char *from, int len,
+		   const struct nls_table *codepage);
+char *smb_strndup_from_utf16(const char *src, const int maxlen,
+			     const bool is_unicode,
+			     const struct nls_table *codepage);
+int smbConvertToUTF16(__le16 *target, const char *source, int srclen,
+		      const struct nls_table *cp, int mapchars);
+char *ksmbd_extract_sharename(struct unicode_map *um, const char *treename);
+#endif
+
+#endif /* _SMB_UNICODE_H */