From 2428083101f6883f979cceffa76cd8440751ffe6 Mon Sep 17 00:00:00 2001 From: Jiayuan Chen Date: Tue, 24 Mar 2026 16:06:44 +0800 Subject: [PATCH] net: qrtr: replace qrtr_tx_flow radix_tree with xarray to fix memory leak MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit __radix_tree_create() allocates and links intermediate nodes into the tree one by one. If a subsequent allocation fails, the already-linked nodes remain in the tree with no corresponding leaf entry. These orphaned internal nodes are never reclaimed because radix_tree_for_each_slot() only visits slots containing leaf values. The radix_tree API is deprecated in favor of xarray. As suggested by Matthew Wilcox, migrate qrtr_tx_flow from radix_tree to xarray instead of fixing the radix_tree itself [1]. xarray properly handles cleanup of internal nodes — xa_destroy() frees all internal xarray nodes when the qrtr_node is released, preventing the leak. [1] https://lore.kernel.org/all/20260225071623.41275-1-jiayuan.chen@linux.dev/T/ Reported-by: syzbot+006987d1be3586e13555@syzkaller.appspotmail.com Closes: https://lore.kernel.org/all/000000000000bfba3a060bf4ffcf@google.com/T/ Fixes: 5fdeb0d372ab ("net: qrtr: Implement outgoing flow control") Signed-off-by: Jiayuan Chen Reviewed-by: Simon Horman Link: https://patch.msgid.link/20260324080645.290197-1-jiayuan.chen@linux.dev Signed-off-by: Jakub Kicinski --- net/qrtr/af_qrtr.c | 31 +++++++++++++------------------ 1 file changed, 13 insertions(+), 18 deletions(-) diff --git a/net/qrtr/af_qrtr.c b/net/qrtr/af_qrtr.c index 55fd2dd37588..d77e9c8212da 100644 --- a/net/qrtr/af_qrtr.c +++ b/net/qrtr/af_qrtr.c @@ -118,7 +118,7 @@ static DEFINE_XARRAY_ALLOC(qrtr_ports); * @ep: endpoint * @ref: reference count for node * @nid: node id - * @qrtr_tx_flow: tree of qrtr_tx_flow, keyed by node << 32 | port + * @qrtr_tx_flow: xarray of qrtr_tx_flow, keyed by node << 32 | port * @qrtr_tx_lock: lock for qrtr_tx_flow inserts * @rx_queue: receive queue * @item: list item for broadcast list @@ -129,7 +129,7 @@ struct qrtr_node { struct kref ref; unsigned int nid; - struct radix_tree_root qrtr_tx_flow; + struct xarray qrtr_tx_flow; struct mutex qrtr_tx_lock; /* for qrtr_tx_flow */ struct sk_buff_head rx_queue; @@ -172,6 +172,7 @@ static void __qrtr_node_release(struct kref *kref) struct qrtr_tx_flow *flow; unsigned long flags; void __rcu **slot; + unsigned long index; spin_lock_irqsave(&qrtr_nodes_lock, flags); /* If the node is a bridge for other nodes, there are possibly @@ -189,11 +190,9 @@ static void __qrtr_node_release(struct kref *kref) skb_queue_purge(&node->rx_queue); /* Free tx flow counters */ - radix_tree_for_each_slot(slot, &node->qrtr_tx_flow, &iter, 0) { - flow = *slot; - radix_tree_iter_delete(&node->qrtr_tx_flow, &iter, slot); + xa_for_each(&node->qrtr_tx_flow, index, flow) kfree(flow); - } + xa_destroy(&node->qrtr_tx_flow); kfree(node); } @@ -228,9 +227,7 @@ static void qrtr_tx_resume(struct qrtr_node *node, struct sk_buff *skb) key = remote_node << 32 | remote_port; - rcu_read_lock(); - flow = radix_tree_lookup(&node->qrtr_tx_flow, key); - rcu_read_unlock(); + flow = xa_load(&node->qrtr_tx_flow, key); if (flow) { spin_lock(&flow->resume_tx.lock); flow->pending = 0; @@ -269,12 +266,13 @@ static int qrtr_tx_wait(struct qrtr_node *node, int dest_node, int dest_port, return 0; mutex_lock(&node->qrtr_tx_lock); - flow = radix_tree_lookup(&node->qrtr_tx_flow, key); + flow = xa_load(&node->qrtr_tx_flow, key); if (!flow) { flow = kzalloc_obj(*flow); if (flow) { init_waitqueue_head(&flow->resume_tx); - if (radix_tree_insert(&node->qrtr_tx_flow, key, flow)) { + if (xa_err(xa_store(&node->qrtr_tx_flow, key, flow, + GFP_KERNEL))) { kfree(flow); flow = NULL; } @@ -326,9 +324,7 @@ static void qrtr_tx_flow_failed(struct qrtr_node *node, int dest_node, unsigned long key = (u64)dest_node << 32 | dest_port; struct qrtr_tx_flow *flow; - rcu_read_lock(); - flow = radix_tree_lookup(&node->qrtr_tx_flow, key); - rcu_read_unlock(); + flow = xa_load(&node->qrtr_tx_flow, key); if (flow) { spin_lock_irq(&flow->resume_tx.lock); flow->tx_failed = 1; @@ -599,7 +595,7 @@ int qrtr_endpoint_register(struct qrtr_endpoint *ep, unsigned int nid) node->nid = QRTR_EP_NID_AUTO; node->ep = ep; - INIT_RADIX_TREE(&node->qrtr_tx_flow, GFP_KERNEL); + xa_init(&node->qrtr_tx_flow); mutex_init(&node->qrtr_tx_lock); qrtr_node_assign(node, nid); @@ -627,6 +623,7 @@ void qrtr_endpoint_unregister(struct qrtr_endpoint *ep) struct qrtr_tx_flow *flow; struct sk_buff *skb; unsigned long flags; + unsigned long index; void __rcu **slot; mutex_lock(&node->ep_lock); @@ -649,10 +646,8 @@ void qrtr_endpoint_unregister(struct qrtr_endpoint *ep) /* Wake up any transmitters waiting for resume-tx from the node */ mutex_lock(&node->qrtr_tx_lock); - radix_tree_for_each_slot(slot, &node->qrtr_tx_flow, &iter, 0) { - flow = *slot; + xa_for_each(&node->qrtr_tx_flow, index, flow) wake_up_interruptible_all(&flow->resume_tx); - } mutex_unlock(&node->qrtr_tx_lock); qrtr_node_release(node);