From: Kaitao Cheng <chengkaitao@kylinos.cn> mainline inclusion from mainline-v7.2-rc1 commit 4a7910ee060d8ce55612f5b3cc267f3a265a3cec category: bugfix bugzilla: https://atomgit.com/openeuler/kernel/issues/9693 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i... -------------------------------- bpf_rb_root_free() detaches the root by copying the current rb_root_cached and then replacing the live root with RB_ROOT_CACHED. It then walks the copied root and drops each object contained in the tree. This leaves the rb node state intact while dropping the object. If the object is refcounted and survives the drop, its bpf_rb_node_kern still contains an owner pointer to the freed root and stale rb tree linkage. If a later bpf_rb_root allocation reuses the same address, bpf_rbtree_remove() can incorrectly pass the owner check and call rb_erase_cached() on a node whose rb pointers belong to the old tree. Mirror the list draining behavior by marking nodes as busy while the root is being detached, then clear the rb node and release the owner before dropping the containing object. This makes surviving nodes unowned and safe to reject from remove or accept for a later add. Fixes: 9c395c1b99bd ("bpf: Add basic bpf_rb_{root,node} support") Signed-off-by: Kaitao Cheng <chengkaitao@kylinos.cn> Acked-by: Yonghong Song <yonghong.song@linux.dev> Link: https://lore.kernel.org/r/20260605094143.5509-1-kaitao.cheng@linux.dev Signed-off-by: Alexei Starovoitov <ast@kernel.org> Conflicts: kernel/bpf/helpers.c [ctx conflicts] Signed-off-by: Pu Lehui <pulehui@huawei.com> --- kernel/bpf/helpers.c | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-) diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c index 58d69b602a76..22a6ec56a116 100644 --- a/kernel/bpf/helpers.c +++ b/kernel/bpf/helpers.c @@ -2022,6 +2022,7 @@ void bpf_rb_root_free(const struct btf_field *field, void *rb_root, struct bpf_spin_lock *spin_lock) { struct rb_root_cached orig_root, *root = rb_root; + struct bpf_rb_node_kern *node; struct rb_node *pos, *n; void *obj; @@ -2030,14 +2031,20 @@ void bpf_rb_root_free(const struct btf_field *field, void *rb_root, __bpf_spin_lock_irqsave(spin_lock); orig_root = *root; + bpf_rbtree_postorder_for_each_entry_safe(pos, n, &orig_root.rb_root) { + node = rb_entry(pos, struct bpf_rb_node_kern, rb_node); + WRITE_ONCE(node->owner, BPF_PTR_POISON); + } *root = RB_ROOT_CACHED; __bpf_spin_unlock_irqrestore(spin_lock); bpf_rbtree_postorder_for_each_entry_safe(pos, n, &orig_root.rb_root) { obj = pos; obj -= field->graph_root.node_offset; - - + node = rb_entry(pos, struct bpf_rb_node_kern, rb_node); + RB_CLEAR_NODE(pos); + /* Ensure __bpf_rbtree_add() sees the node as unlinked. */ + smp_store_release(&node->owner, NULL); migrate_disable(); __bpf_obj_drop_impl(obj, field->graph_root.value_rec); migrate_enable(); -- 2.34.1