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, 77 insertions, 0 deletions

diff --git a/tools/objtool/sync-check.sh b/tools/objtool/sync-check.sh
new file mode 100755
index 000000000..e38167ca5
--- /dev/null
+++ b/tools/objtool/sync-check.sh
@@ -0,0 +1,77 @@
+#!/bin/sh
+# SPDX-License-Identifier: GPL-2.0
+
+if [ -z "$SRCARCH" ]; then
+	echo 'sync-check.sh: error: missing $SRCARCH environment variable' >&2
+	exit 1
+fi
+
+FILES="include/linux/objtool_types.h"
+
+if [ "$SRCARCH" = "x86" ]; then
+FILES="$FILES
+arch/x86/include/asm/nops.h
+arch/x86/include/asm/inat_types.h
+arch/x86/include/asm/orc_types.h
+arch/x86/include/asm/emulate_prefix.h
+arch/x86/lib/x86-opcode-map.txt
+arch/x86/tools/gen-insn-attr-x86.awk
+include/linux/interval_tree_generic.h
+include/linux/livepatch_external.h
+include/linux/static_call_types.h
+"
+
+SYNC_CHECK_FILES='
+arch/x86/include/asm/inat.h
+arch/x86/include/asm/insn.h
+arch/x86/lib/inat.c
+arch/x86/lib/insn.c
+'
+fi
+
+check_2 () {
+  file1=$1
+  file2=$2
+
+  shift
+  shift
+
+  cmd="diff $* $file1 $file2 > /dev/null"
+
+  test -f $file2 && {
+    eval $cmd || {
+      echo "Warning: Kernel ABI header at '$file1' differs from latest version at '$file2'" >&2
+      echo diff -u $file1 $file2
+    }
+  }
+}
+
+check () {
+  file=$1
+
+  shift
+
+  check_2 tools/$file $file $*
+}
+
+if [ ! -d ../../kernel ] || [ ! -d ../../tools ] || [ ! -d ../objtool ]; then
+	exit 0
+fi
+
+cd ../..
+
+while read -r file_entry; do
+    if [ -z "$file_entry" ]; then
+	continue
+    fi
+
+    check $file_entry
+done <<EOF
+$FILES
+EOF
+
+if [ "$SRCARCH" = "x86" ]; then
+	for i in $SYNC_CHECK_FILES; do
+		check $i '-I "^.*\/\*.*__ignore_sync_check__.*\*\/.*$"'
+	done
+fi