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/xfs/xfs_hooks.c | 52 ++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 52 insertions(+) create mode 100644 fs/xfs/xfs_hooks.c (limited to 'fs/xfs/xfs_hooks.c') diff --git a/fs/xfs/xfs_hooks.c b/fs/xfs/xfs_hooks.c new file mode 100644 index 000000000..a09109e69 --- /dev/null +++ b/fs/xfs/xfs_hooks.c @@ -0,0 +1,52 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * Copyright (c) 2022-2024 Oracle. All Rights Reserved. + * Author: Darrick J. Wong + */ +#include "xfs_platform.h" +#include "xfs_fs.h" +#include "xfs_shared.h" +#include "xfs_format.h" +#include "xfs_trans_resv.h" +#include "xfs_mount.h" +#include "xfs_ag.h" +#include "xfs_trace.h" + +/* Initialize a notifier chain. */ +void +xfs_hooks_init( + struct xfs_hooks *chain) +{ + BLOCKING_INIT_NOTIFIER_HEAD(&chain->head); +} + +/* Make it so a function gets called whenever we hit a certain hook point. */ +int +xfs_hooks_add( + struct xfs_hooks *chain, + struct xfs_hook *hook) +{ + ASSERT(hook->nb.notifier_call != NULL); + BUILD_BUG_ON(offsetof(struct xfs_hook, nb) != 0); + + return blocking_notifier_chain_register(&chain->head, &hook->nb); +} + +/* Remove a previously installed hook. */ +void +xfs_hooks_del( + struct xfs_hooks *chain, + struct xfs_hook *hook) +{ + blocking_notifier_chain_unregister(&chain->head, &hook->nb); +} + +/* Call a hook. Returns the NOTIFY_* value returned by the last hook. */ +int +xfs_hooks_call( + struct xfs_hooks *chain, + unsigned long val, + void *priv) +{ + return blocking_notifier_call_chain(&chain->head, val, priv); +} -- cgit v1.3.1