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/lowcomms.h | 55 +++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 55 insertions(+) create mode 100644 fs/dlm/lowcomms.h (limited to 'fs/dlm/lowcomms.h') diff --git a/fs/dlm/lowcomms.h b/fs/dlm/lowcomms.h new file mode 100644 index 000000000..fd0df604e --- /dev/null +++ b/fs/dlm/lowcomms.h @@ -0,0 +1,55 @@ +/* SPDX-License-Identifier: GPL-2.0-only */ +/****************************************************************************** +******************************************************************************* +** +** Copyright (C) Sistina Software, Inc. 1997-2003 All rights reserved. +** Copyright (C) 2004-2009 Red Hat, Inc. All rights reserved. +** +** +******************************************************************************* +******************************************************************************/ + +#ifndef __LOWCOMMS_DOT_H__ +#define __LOWCOMMS_DOT_H__ + +#include "dlm_internal.h" + +#define DLM_MIDCOMMS_OPT_LEN sizeof(struct dlm_opts) +#define DLM_MAX_APP_BUFSIZE (DLM_MAX_SOCKET_BUFSIZE - \ + DLM_MIDCOMMS_OPT_LEN) + +#define CONN_HASH_SIZE 32 + +/* This is deliberately very simple because most clusters have simple + * sequential nodeids, so we should be able to go straight to a connection + * struct in the array + */ +static inline int nodeid_hash(int nodeid) +{ + return nodeid & (CONN_HASH_SIZE-1); +} + +/* check if dlm is running */ +bool dlm_lowcomms_is_running(void); + +int dlm_lowcomms_start(void); +void dlm_lowcomms_shutdown(void); +void dlm_lowcomms_shutdown_node(int nodeid, bool force); +void dlm_lowcomms_stop(void); +void dlm_lowcomms_init(void); +void dlm_lowcomms_exit(void); +int dlm_lowcomms_close(int nodeid); +struct dlm_msg *dlm_lowcomms_new_msg(int nodeid, int len, char **ppc, + void (*cb)(void *data), void *data); +void dlm_lowcomms_commit_msg(struct dlm_msg *msg); +void dlm_lowcomms_put_msg(struct dlm_msg *msg); +int dlm_lowcomms_resend_msg(struct dlm_msg *msg); +int dlm_lowcomms_connect_node(int nodeid); +int dlm_lowcomms_nodes_set_mark(int nodeid, unsigned int mark); +int dlm_lowcomms_addr(int nodeid, struct sockaddr_storage *addr); +void dlm_midcomms_receive_done(int nodeid); +struct kmem_cache *dlm_lowcomms_writequeue_cache_create(void); +struct kmem_cache *dlm_lowcomms_msg_cache_create(void); + +#endif /* __LOWCOMMS_DOT_H__ */ + -- cgit v1.3.1