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, 22 insertions, 0 deletions

diff --git a/fs/smb/server/ndr.h b/fs/smb/server/ndr.h
new file mode 100644
index 000000000..f3c108c8c
--- /dev/null
+++ b/fs/smb/server/ndr.h
@@ -0,0 +1,22 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ *   Copyright (C) 2020 Samsung Electronics Co., Ltd.
+ *   Author(s): Namjae Jeon <linkinjeon@kernel.org>
+ */
+
+struct ndr {
+	char	*data;
+	int	offset;
+	int	length;
+};
+
+#define NDR_NTSD_OFFSETOF	0xA0
+
+int ndr_encode_dos_attr(struct ndr *n, struct xattr_dos_attrib *da);
+int ndr_decode_dos_attr(struct ndr *n, struct xattr_dos_attrib *da);
+int ndr_encode_posix_acl(struct ndr *n, struct mnt_idmap *idmap,
+			 struct inode *inode, struct xattr_smb_acl *acl,
+			 struct xattr_smb_acl *def_acl);
+int ndr_encode_v4_ntacl(struct ndr *n, struct xattr_ntacl *acl);
+int ndr_encode_v3_ntacl(struct ndr *n, struct xattr_ntacl *acl);
+int ndr_decode_v4_ntacl(struct ndr *n, struct xattr_ntacl *acl);