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, 14 insertions, 0 deletions

diff --git a/fs/coda/Makefile b/fs/coda/Makefile
new file mode 100644
index 000000000..78befb836
--- /dev/null
+++ b/fs/coda/Makefile
@@ -0,0 +1,14 @@
+# SPDX-License-Identifier: GPL-2.0-only
+#
+# Makefile for the Linux Coda filesystem routines.
+#
+
+obj-$(CONFIG_CODA_FS) += coda.o
+
+coda-objs := psdev.o cache.o cnode.o inode.o dir.o file.o upcall.o \
+	     coda_linux.o symlink.o pioctl.o
+coda-$(CONFIG_SYSCTL) += sysctl.o
+
+# If you want debugging output, please uncomment the following line.
+
+# ccflags-y := -DDEBUG -DDEBUG_SMB_MALLOC=1