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 --- tools/testing/shared/maple-shared.h | 24 ++++++++++++++++++++++++ 1 file changed, 24 insertions(+) create mode 100644 tools/testing/shared/maple-shared.h (limited to 'tools/testing/shared/maple-shared.h') diff --git a/tools/testing/shared/maple-shared.h b/tools/testing/shared/maple-shared.h new file mode 100644 index 000000000..2a1e9a859 --- /dev/null +++ b/tools/testing/shared/maple-shared.h @@ -0,0 +1,24 @@ +/* SPDX-License-Identifier: GPL-2.0+ */ +#ifndef __MAPLE_SHARED_H__ +#define __MAPLE_SHARED_H__ + +#define CONFIG_DEBUG_MAPLE_TREE +#define CONFIG_MAPLE_SEARCH +#define MAPLE_32BIT (MAPLE_NODE_SLOTS > 31) +#include "shared.h" +#include +#include +#include "linux/init.h" + +void maple_rcu_cb(struct rcu_head *head); +#define rcu_cb maple_rcu_cb + +#define kfree_rcu(_struct, _memb) \ +do { \ + typeof(_struct) _p_struct = (_struct); \ + \ + call_rcu(&((_p_struct)->_memb), rcu_cb); \ +} while(0); + + +#endif /* __MAPLE_SHARED_H__ */ -- cgit v1.3.1