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/nilfs2/btree.h | 65 +++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 65 insertions(+) create mode 100644 fs/nilfs2/btree.h (limited to 'fs/nilfs2/btree.h') diff --git a/fs/nilfs2/btree.h b/fs/nilfs2/btree.h new file mode 100644 index 000000000..2a220f716 --- /dev/null +++ b/fs/nilfs2/btree.h @@ -0,0 +1,65 @@ +/* SPDX-License-Identifier: GPL-2.0+ */ +/* + * NILFS B-tree. + * + * Copyright (C) 2005-2008 Nippon Telegraph and Telephone Corporation. + * + * Written by Koji Sato. + */ + +#ifndef _NILFS_BTREE_H +#define _NILFS_BTREE_H + +#include +#include +#include +#include /* nilfs_btree_node */ +#include "btnode.h" +#include "bmap.h" + +/** + * struct nilfs_btree_path - A path on which B-tree operations are executed + * @bp_bh: buffer head of node block + * @bp_sib_bh: buffer head of sibling node block + * @bp_index: index of child node + * @bp_oldreq: ptr end request for old ptr + * @bp_newreq: ptr alloc request for new ptr + * @bp_ctxt: context information for changing the key of a b-tree node block + * @bp_op: rebalance operation + */ +struct nilfs_btree_path { + struct buffer_head *bp_bh; + struct buffer_head *bp_sib_bh; + int bp_index; + union nilfs_bmap_ptr_req bp_oldreq; + union nilfs_bmap_ptr_req bp_newreq; + struct nilfs_btnode_chkey_ctxt bp_ctxt; + void (*bp_op)(struct nilfs_bmap *, struct nilfs_btree_path *, + int, __u64 *, __u64 *); +}; + +#define NILFS_BTREE_ROOT_SIZE NILFS_BMAP_SIZE +#define NILFS_BTREE_ROOT_NCHILDREN_MAX \ + ((NILFS_BTREE_ROOT_SIZE - sizeof(struct nilfs_btree_node)) / \ + (sizeof(__le64 /* dkey */) + sizeof(__le64 /* dptr */))) +#define NILFS_BTREE_ROOT_NCHILDREN_MIN 0 +#define NILFS_BTREE_NODE_EXTRA_PAD_SIZE (sizeof(__le64)) +#define NILFS_BTREE_NODE_NCHILDREN_MAX(nodesize) \ + (((nodesize) - sizeof(struct nilfs_btree_node) - \ + NILFS_BTREE_NODE_EXTRA_PAD_SIZE) / \ + (sizeof(__le64 /* dkey */) + sizeof(__le64 /* dptr */))) +#define NILFS_BTREE_NODE_NCHILDREN_MIN(nodesize) \ + ((NILFS_BTREE_NODE_NCHILDREN_MAX(nodesize) - 1) / 2 + 1) +#define NILFS_BTREE_KEY_MIN ((__u64)0) +#define NILFS_BTREE_KEY_MAX (~(__u64)0) + +extern struct kmem_cache *nilfs_btree_path_cache; + +int nilfs_btree_init(struct nilfs_bmap *); +int nilfs_btree_convert_and_insert(struct nilfs_bmap *, __u64, __u64, + const __u64 *, const __u64 *, int); +void nilfs_btree_init_gc(struct nilfs_bmap *); + +int nilfs_btree_broken_node_block(struct buffer_head *bh); + +#endif /* _NILFS_BTREE_H */ -- cgit v1.3.1