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/btrfs/tree-mod-log.h | 58 +++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 58 insertions(+) create mode 100644 fs/btrfs/tree-mod-log.h (limited to 'fs/btrfs/tree-mod-log.h') diff --git a/fs/btrfs/tree-mod-log.h b/fs/btrfs/tree-mod-log.h new file mode 100644 index 000000000..1c1256604 --- /dev/null +++ b/fs/btrfs/tree-mod-log.h @@ -0,0 +1,58 @@ +/* SPDX-License-Identifier: GPL-2.0 */ + +#ifndef BTRFS_TREE_MOD_LOG_H +#define BTRFS_TREE_MOD_LOG_H + +#include + +struct extent_buffer; +struct btrfs_fs_info; +struct btrfs_path; +struct btrfs_root; +struct btrfs_seq_list; + +/* Represents a tree mod log user. */ +struct btrfs_seq_list { + struct list_head list; + u64 seq; +}; + +#define BTRFS_SEQ_LIST_INIT(name) { .list = LIST_HEAD_INIT((name).list), .seq = 0 } +#define BTRFS_SEQ_LAST ((u64)-1) + +enum btrfs_mod_log_op { + BTRFS_MOD_LOG_KEY_REPLACE, + BTRFS_MOD_LOG_KEY_ADD, + BTRFS_MOD_LOG_KEY_REMOVE, + BTRFS_MOD_LOG_KEY_REMOVE_WHILE_FREEING, + BTRFS_MOD_LOG_KEY_REMOVE_WHILE_MOVING, + BTRFS_MOD_LOG_MOVE_KEYS, + BTRFS_MOD_LOG_ROOT_REPLACE, +}; + +u64 btrfs_get_tree_mod_seq(struct btrfs_fs_info *fs_info, + struct btrfs_seq_list *elem); +void btrfs_put_tree_mod_seq(struct btrfs_fs_info *fs_info, + struct btrfs_seq_list *elem); +int btrfs_tree_mod_log_insert_root(struct extent_buffer *old_root, + struct extent_buffer *new_root, + bool log_removal); +int btrfs_tree_mod_log_insert_key(const struct extent_buffer *eb, int slot, + enum btrfs_mod_log_op op); +int btrfs_tree_mod_log_free_eb(struct extent_buffer *eb); +struct extent_buffer *btrfs_tree_mod_log_rewind(struct btrfs_fs_info *fs_info, + struct extent_buffer *eb, + u64 time_seq); +struct extent_buffer *btrfs_get_old_root(struct btrfs_root *root, u64 time_seq); +int btrfs_old_root_level(struct btrfs_root *root, u64 time_seq); +int btrfs_tree_mod_log_eb_copy(struct extent_buffer *dst, + const struct extent_buffer *src, + unsigned long dst_offset, + unsigned long src_offset, + int nr_items); +int btrfs_tree_mod_log_insert_move(const struct extent_buffer *eb, + int dst_slot, int src_slot, + int nr_items); +u64 btrfs_tree_mod_log_lowest_seq(struct btrfs_fs_info *fs_info); + +#endif -- cgit v1.3.1