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/drivers/video/fbdev/c2p.h b/drivers/video/fbdev/c2p.h
new file mode 100644
index 000000000..6c38d4042
--- /dev/null
+++ b/drivers/video/fbdev/c2p.h
@@ -0,0 +1,19 @@
+/*
+ *  Fast C2P (Chunky-to-Planar) Conversion
+ *
+ *  Copyright (C) 2003-2008 Geert Uytterhoeven
+ *
+ *  This file is subject to the terms and conditions of the GNU General Public
+ *  License. See the file COPYING in the main directory of this archive
+ *  for more details.
+ */
+
+#include <linux/types.h>
+
+extern void c2p_planar(void *dst, const void *src, u32 dx, u32 dy, u32 width,
+		       u32 height, u32 dst_nextline, u32 dst_nextplane,
+		       u32 src_nextline, u32 bpp);
+
+extern void c2p_iplan2(void *dst, const void *src, u32 dx, u32 dy, u32 width,
+		       u32 height, u32 dst_nextline, u32 src_nextline,
+		       u32 bpp);