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, 33 insertions, 0 deletions

diff --git a/sound/usb/midi2.h b/sound/usb/midi2.h
new file mode 100644
index 000000000..94a65fcbd
--- /dev/null
+++ b/sound/usb/midi2.h
@@ -0,0 +1,33 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+#ifndef __USB_AUDIO_MIDI2_H
+#define __USB_AUDIO_MIDI2_H
+
+#include "midi.h"
+
+#if IS_ENABLED(CONFIG_SND_USB_AUDIO_MIDI_V2)
+int snd_usb_midi_v2_create(struct snd_usb_audio *chip,
+			   struct usb_interface *iface,
+			   const struct snd_usb_audio_quirk *quirk,
+			   unsigned int usb_id);
+void snd_usb_midi_v2_suspend_all(struct snd_usb_audio *chip);
+void snd_usb_midi_v2_resume_all(struct snd_usb_audio *chip);
+void snd_usb_midi_v2_disconnect_all(struct snd_usb_audio *chip);
+void snd_usb_midi_v2_free_all(struct snd_usb_audio *chip);
+#else /* CONFIG_SND_USB_AUDIO_MIDI_V2 */
+/* fallback to MIDI 1.0 creation */
+static inline int snd_usb_midi_v2_create(struct snd_usb_audio *chip,
+					 struct usb_interface *iface,
+					 const struct snd_usb_audio_quirk *quirk,
+					 unsigned int usb_id)
+{
+	return __snd_usbmidi_create(chip->card, iface, &chip->midi_list,
+				    quirk, usb_id, &chip->num_rawmidis);
+}
+
+static inline void snd_usb_midi_v2_suspend_all(struct snd_usb_audio *chip) {}
+static inline void snd_usb_midi_v2_resume_all(struct snd_usb_audio *chip) {}
+static inline void snd_usb_midi_v2_disconnect_all(struct snd_usb_audio *chip) {}
+static inline void snd_usb_midi_v2_free_all(struct snd_usb_audio *chip) {}
+#endif /* CONFIG_SND_USB_AUDIO_MIDI_V2 */
+
+#endif /* __USB_AUDIO_MIDI2_H */