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, 19 insertions, 0 deletions

diff --git a/fs/udf/Kconfig b/fs/udf/Kconfig
new file mode 100644
index 000000000..8f7ce30d4
--- /dev/null
+++ b/fs/udf/Kconfig
@@ -0,0 +1,19 @@
+# SPDX-License-Identifier: GPL-2.0-only
+config UDF_FS
+	tristate "UDF file system support"
+	select BUFFER_HEAD
+	select CRC_ITU_T
+	select NLS
+	select LEGACY_DIRECT_IO
+	help
+	  This is a file system used on some CD-ROMs and DVDs. Since the
+	  file system is supported by multiple operating systems and is more
+	  compatible with standard unix file systems, it is also suitable for
+	  removable USB disks. Say Y if you intend to mount DVD discs or CDRW's
+	  written in packet mode, or if you want to use UDF for removable USB
+	  disks. Please read <file:Documentation/filesystems/udf.rst>.
+
+	  To compile this file system support as a module, choose M here: the
+	  module will be called udf.
+
+	  If unsure, say N.