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/arm/common/vlock.h | 21 +++++++++++++++++++++ 1 file changed, 21 insertions(+) create mode 100644 arch/arm/common/vlock.h (limited to 'arch/arm/common/vlock.h') diff --git a/arch/arm/common/vlock.h b/arch/arm/common/vlock.h new file mode 100644 index 000000000..422429781 --- /dev/null +++ b/arch/arm/common/vlock.h @@ -0,0 +1,21 @@ +/* SPDX-License-Identifier: GPL-2.0-only */ +/* + * vlock.h - simple voting lock implementation + * + * Created by: Dave Martin, 2012-08-16 + * Copyright: (C) 2012-2013 Linaro Limited + */ + +#ifndef __VLOCK_H +#define __VLOCK_H + +#include + +/* Offsets and sizes are rounded to a word (4 bytes) */ +#define VLOCK_OWNER_OFFSET 0 +#define VLOCK_VOTING_OFFSET 4 +#define VLOCK_VOTING_SIZE ((MAX_CPUS_PER_CLUSTER + 3) / 4 * 4) +#define VLOCK_SIZE (VLOCK_VOTING_OFFSET + VLOCK_VOTING_SIZE) +#define VLOCK_OWNER_NONE 0 + +#endif /* ! __VLOCK_H */ -- cgit v1.3.1