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[95.169.12.199]) by smtp.gmail.com with ESMTPSA id a92af1059eb24-145ac67c505sm13792059c88.5.2026.09.26.10.33.20 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 26 Sep 2026 10:33:23 -0700 (PDT) From: Chengfeng Ye To: "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Simon Horman , Mark Brown , Christian Brauner , Antoine Tenart Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org, Chengfeng Ye , stable@vger.kernel.org Subject: [PATCH net] net-sysfs: release the TX queue tracker before allowing reuse Date: Sun, 27 Sep 2026 01:33:15 +0800 Message-ID: <20260926173315.2452612-1-nicoyip.dev@gmail.com> X-Mailer: git-send-email 2.43.0 Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit An interrupted sysfs_rtnl_lock() can drop the last kobject reference to a removed TX queue without holding RTNL. netdev_queue_release() clears the kobject before releasing queue->dev_tracker, allowing the queue to be re-added while the old release still needs the shared tracker slot: CPU 0 CPU 1 netdev_queue_release() memset(kobj, 0, sizeof(*kobj)) netdev_queue_add_kobject() state_initialized is clear netdev_hold() installs new tracker netdev_put() releases the new tracker With CONFIG_NET_DEV_REFCNT_TRACKER enabled, the old tracker is leaked and the new lifetime's tracker is released prematurely. A later queue release then reports a double release. The numeric device references remain balanced. The kernel reported: ref_tracker: reference already released. ref_tracker: allocated in: netdev_queue_update_kobjects+0x23d/0x5c0 netif_set_real_num_tx_queues+0x111/0x820 veth_set_channels+0x327/0x930 ethtool_set_channels+0x3ee/0x490 ref_tracker: freed in: netdev_queue_release+0xbd/0x130 kobject_put+0x1f9/0x280 sysfs_rtnl_lock+0x18b/0x1f0 xps_rxqs_show+0xad/0x250 WARNING: lib/ref_tracker.c:322 at ref_tracker_free+0x49e/0x6d0 Call Trace: netdev_queue_release+0xbd/0x130 kobject_put+0x1f9/0x280 netdev_queue_update_kobjects+0x3f9/0x5c0 netif_set_real_num_tx_queues+0x111/0x820 veth_set_channels+0x327/0x930 ethtool_set_channels+0x3ee/0x490 Release the tracker before clearing the kobject. Use a full memory barrier to order the tracker access before clearing state_initialized, paired with the control dependency from that check to the new tracker allocation. Keep the device reference until after the reset so that the queue storage remains alive throughout the callback's accesses. Fixes: b0b6fcfa6ad8 ("net-sysfs: remove rtnl_trylock from queue attributes") Cc: stable@vger.kernel.org Signed-off-by: Chengfeng Ye --- net/core/net-sysfs.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/net/core/net-sysfs.c b/net/core/net-sysfs.c index 352173df7578..b9aadc4c000c 100644 --- a/net/core/net-sysfs.c +++ b/net/core/net-sysfs.c @@ -1906,8 +1906,11 @@ static void netdev_queue_release(struct kobject *kobj) { struct netdev_queue *queue = to_netdev_queue(kobj); + netdev_tracker_free(queue->dev, &queue->dev_tracker); + /* Finish using the tracker before allowing the queue to be re-added. */ + smp_mb(); memset(kobj, 0, sizeof(*kobj)); - netdev_put(queue->dev, &queue->dev_tracker); + __dev_put(queue->dev); } static const struct ns_common *netdev_queue_namespace(const struct kobject *kobj) -- 2.43.0