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/dlm/rcom.h | 26 ++++++++++++++++++++++++++ 1 file changed, 26 insertions(+) create mode 100644 fs/dlm/rcom.h (limited to 'fs/dlm/rcom.h') diff --git a/fs/dlm/rcom.h b/fs/dlm/rcom.h new file mode 100644 index 000000000..765926ae0 --- /dev/null +++ b/fs/dlm/rcom.h @@ -0,0 +1,26 @@ +/* SPDX-License-Identifier: GPL-2.0-only */ +/****************************************************************************** +******************************************************************************* +** +** Copyright (C) Sistina Software, Inc. 1997-2003 All rights reserved. +** Copyright (C) 2005-2007 Red Hat, Inc. All rights reserved. +** +** +******************************************************************************* +******************************************************************************/ + +#ifndef __RCOM_DOT_H__ +#define __RCOM_DOT_H__ + +int dlm_rcom_status(struct dlm_ls *ls, int nodeid, uint32_t status_flags, + uint64_t seq); +int dlm_rcom_names(struct dlm_ls *ls, int nodeid, char *last_name, + int last_len, uint64_t seq); +int dlm_send_rcom_lookup(struct dlm_rsb *r, int dir_nodeid, uint64_t seq); +int dlm_send_rcom_lock(struct dlm_rsb *r, struct dlm_lkb *lkb, uint64_t seq); +void dlm_receive_rcom(struct dlm_ls *ls, const struct dlm_rcom *rc, + int nodeid); +int dlm_send_ls_not_ready(int nodeid, const struct dlm_rcom *rc_in); + +#endif + -- cgit v1.3.1