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/lockd/share.h | 33 +++++++++++++++++++++++++++++++++ 1 file changed, 33 insertions(+) create mode 100644 fs/lockd/share.h (limited to 'fs/lockd/share.h') diff --git a/fs/lockd/share.h b/fs/lockd/share.h new file mode 100644 index 000000000..1ec3ccdb2 --- /dev/null +++ b/fs/lockd/share.h @@ -0,0 +1,33 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* + * DOS share management for lockd. + * + * Copyright (C) 1996, Olaf Kirch + */ + +#ifndef _LOCKD_SHARE_H +#define _LOCKD_SHARE_H + +/* Synthetic svid for lockowner lookup during share operations */ +#define LOCKD_SHARE_SVID (~(u32)0) + +/* + * DOS share for a specific file + */ +struct lockd_share { + struct lockd_share * s_next; /* linked list */ + struct nlm_host * s_host; /* client host */ + struct nlm_file * s_file; /* shared file */ + struct xdr_netobj s_owner; /* owner handle */ + u32 s_access; /* access mode */ + u32 s_mode; /* deny mode */ +}; + +__be32 nlmsvc_share_file(struct nlm_host *host, struct nlm_file *file, + struct xdr_netobj *oh, u32 access, u32 mode); +__be32 nlmsvc_unshare_file(struct nlm_host *host, struct nlm_file *file, + struct xdr_netobj *oh); +void nlmsvc_traverse_shares(struct nlm_host *, struct nlm_file *, + nlm_host_match_fn_t); + +#endif /* _LOCKD_SHARE_H */ -- cgit v1.3.1