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, 32 insertions, 0 deletions

diff --git a/scripts/depmod.sh b/scripts/depmod.sh
new file mode 100755
index 000000000..3c34fecac
--- /dev/null
+++ b/scripts/depmod.sh
@@ -0,0 +1,32 @@
+#!/bin/sh
+# SPDX-License-Identifier: GPL-2.0
+#
+# A depmod wrapper
+
+if test $# -ne 1; then
+	echo "Usage: $0 <kernelrelease>" >&2
+	exit 1
+fi
+
+KERNELRELEASE=$1
+
+: ${DEPMOD:=depmod}
+
+if ! test -r "${objtree}/System.map" ; then
+	echo "Warning: modules_install: missing 'System.map' file. Skipping depmod." >&2
+	exit 0
+fi
+
+# legacy behavior: "depmod" in /sbin, no /sbin in PATH
+PATH="$PATH:/sbin"
+if [ -z $(command -v $DEPMOD) ]; then
+	echo "Warning: 'make modules_install' requires $DEPMOD. Please install it." >&2
+	echo "This is probably in the kmod package." >&2
+	exit 0
+fi
+
+set -- -ae -F "${objtree}/System.map"
+if test -n "$INSTALL_MOD_PATH"; then
+	set -- "$@" -b "$INSTALL_MOD_PATH"
+fi
+exec "$DEPMOD" "$@" "$KERNELRELEASE"