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 --- fs/jfs/jfs_lock.h | 39 +++++++++++++++++++++++++++++++++++++++ 1 file changed, 39 insertions(+) create mode 100644 fs/jfs/jfs_lock.h (limited to 'fs/jfs/jfs_lock.h') diff --git a/fs/jfs/jfs_lock.h b/fs/jfs/jfs_lock.h new file mode 100644 index 000000000..feb37dd9d --- /dev/null +++ b/fs/jfs/jfs_lock.h @@ -0,0 +1,39 @@ +/* SPDX-License-Identifier: GPL-2.0-or-later */ +/* + * Copyright (C) International Business Machines Corp., 2000-2001 + * Portions Copyright (C) Christoph Hellwig, 2001-2002 + */ +#ifndef _H_JFS_LOCK +#define _H_JFS_LOCK + +#include +#include +#include + +/* + * jfs_lock.h + */ + +/* + * Conditional sleep where condition is protected by spinlock + * + * lock_cmd and unlock_cmd take and release the spinlock + */ +#define __SLEEP_COND(wq, cond, lock_cmd, unlock_cmd) \ +do { \ + DECLARE_WAITQUEUE(__wait, current); \ + \ + add_wait_queue(&wq, &__wait); \ + for (;;) { \ + set_current_state(TASK_UNINTERRUPTIBLE);\ + if (cond) \ + break; \ + unlock_cmd; \ + io_schedule(); \ + lock_cmd; \ + } \ + __set_current_state(TASK_RUNNING); \ + remove_wait_queue(&wq, &__wait); \ +} while (0) + +#endif /* _H_JFS_LOCK */ -- cgit v1.3.1