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, 21 insertions, 0 deletions

diff --git a/scripts/atomic/gen-atomics.sh b/scripts/atomic/gen-atomics.sh
new file mode 100755
index 000000000..02508d0d6
--- /dev/null
+++ b/scripts/atomic/gen-atomics.sh
@@ -0,0 +1,21 @@
+#!/bin/sh
+# SPDX-License-Identifier: GPL-2.0
+#
+# Generate atomic headers
+
+ATOMICDIR=$(dirname $0)
+ATOMICTBL=${ATOMICDIR}/atomics.tbl
+LINUXDIR=${ATOMICDIR}/../..
+
+cat <<EOF |
+gen-atomic-instrumented.sh      linux/atomic/atomic-instrumented.h
+gen-atomic-long.sh              linux/atomic/atomic-long.h
+gen-atomic-fallback.sh          linux/atomic/atomic-arch-fallback.h
+gen-rust-atomic-helpers.sh      ../rust/helpers/atomic.c
+EOF
+while read script header args; do
+	/bin/sh ${ATOMICDIR}/${script} ${ATOMICTBL} ${args} > ${LINUXDIR}/include/${header}
+	HASH="$(sha1sum ${LINUXDIR}/include/${header})"
+	HASH="${HASH%% *}"
+	printf "// %s\n" "${HASH}" >> ${LINUXDIR}/include/${header}
+done