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, 48 insertions, 0 deletions

diff --git a/fs/nfs/netns.h b/fs/nfs/netns.h
new file mode 100644
index 000000000..366585791
--- /dev/null
+++ b/fs/nfs/netns.h
@@ -0,0 +1,48 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * NFS-private data for each "struct net".  Accessed with net_generic().
+ */
+
+#ifndef __NFS_NETNS_H__
+#define __NFS_NETNS_H__
+
+#include <linux/nfs4.h>
+#include <net/net_namespace.h>
+#include <net/netns/generic.h>
+#include <linux/sunrpc/stats.h>
+
+struct bl_dev_msg {
+	int32_t status;
+	uint32_t major, minor;
+};
+
+struct nfs_netns_client;
+
+struct nfs_net {
+	struct cache_detail *nfs_dns_resolve;
+	struct rpc_pipe *bl_device_pipe;
+	struct bl_dev_msg bl_mount_reply;
+	wait_queue_head_t bl_wq;
+	struct mutex bl_mutex;
+	struct list_head nfs_client_list;
+	struct list_head nfs_volume_list;
+#if IS_ENABLED(CONFIG_NFS_V4)
+	struct idr cb_ident_idr; /* Protected by nfs_client_lock */
+	unsigned short nfs_callback_tcpport;
+	unsigned short nfs_callback_tcpport6;
+	int cb_users[NFS4_MAX_MINOR_VERSION + 1];
+	struct list_head nfs4_data_server_cache;
+	spinlock_t nfs4_data_server_lock;
+#endif /* CONFIG_NFS_V4 */
+	struct nfs_netns_client *nfs_client;
+	spinlock_t nfs_client_lock;
+	ktime_t boot_time;
+	struct rpc_stat rpcstats;
+#ifdef CONFIG_PROC_FS
+	struct proc_dir_entry *proc_nfsfs;
+#endif
+};
+
+extern unsigned int nfs_net_id;
+
+#endif