From 6668ed271eaefaa63e686bdfbedaeb7b8e492722 Mon Sep 17 00:00:00 2001 From: Kumar Kartikeya Dwivedi Date: Fri, 4 Sep 2026 10:43:19 +0200 Subject: selftests/bpf: Reject graph kptr use after RCU unlock 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 Link: https://lore.kernel.org/r/20260904084325.52250-7-memxor@gmail.com Signed-off-by: Alexei Starovoitov --- arch/riscv/tools/relocs_check.sh | 28 ++++++++++++++++++++++++++++ 1 file changed, 28 insertions(+) create mode 100755 arch/riscv/tools/relocs_check.sh (limited to 'arch/riscv/tools') diff --git a/arch/riscv/tools/relocs_check.sh b/arch/riscv/tools/relocs_check.sh new file mode 100755 index 000000000..742993e6a --- /dev/null +++ b/arch/riscv/tools/relocs_check.sh @@ -0,0 +1,28 @@ +#!/bin/sh +# SPDX-License-Identifier: GPL-2.0-or-later +# Based on powerpc relocs_check.sh + +# This script checks the relocations of a vmlinux for "suspicious" +# relocations. + +if [ $# -lt 3 ]; then + echo "$0 [path to objdump] [path to nm] [path to vmlinux]" 1>&2 + exit 1 +fi + +bad_relocs=$( +${srctree}/scripts/relocs_check.sh "$@" | + # These relocations are okay + # R_RISCV_RELATIVE + # R_RISCV_NONE + grep -F -w -v 'R_RISCV_RELATIVE +R_RISCV_NONE' +) + +if [ -z "$bad_relocs" ]; then + exit 0 +fi + +num_bad=$(echo "$bad_relocs" | wc -l) +echo "WARNING: $num_bad bad relocations" +echo "$bad_relocs" -- cgit v1.3.1