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, 45 insertions, 0 deletions

diff --git a/drivers/most/Kconfig b/drivers/most/Kconfig
new file mode 100644
index 000000000..69c9e728b
--- /dev/null
+++ b/drivers/most/Kconfig
@@ -0,0 +1,45 @@
+# SPDX-License-Identifier: GPL-2.0
+menuconfig MOST
+	tristate "MOST (Media Oriented Systems Transport) support"
+	depends on HAS_DMA && CONFIGFS_FS
+	default n
+	help
+	  Say Y here if you want to enable MOST support.
+	  This driver needs at least one additional component to enable the
+	  desired access from userspace (e.g. character devices) and one that
+	  matches the network controller's hardware interface (e.g. USB).
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called most_core.
+
+	  If in doubt, say N here.
+
+if MOST
+config MOST_USB_HDM
+	tristate "USB"
+	depends on USB
+	help
+	  Say Y here if you want to connect via USB to network transceiver.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called most_usb.
+
+config MOST_CDEV
+	tristate "Cdev"
+
+	help
+	  Say Y here if you want to commumicate via character devices.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called most_cdev.
+
+config MOST_SND
+	tristate "Sound"
+	depends on SND
+	select SND_PCM
+	help
+	  Say Y here if you want to commumicate via ALSA/sound devices.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called most_sound.
+endif