From 56e20c3d8ad340bbfc90221c4aae1c870485fb57 Mon Sep 17 00:00:00 2001 From: Cen Zhang Date: Mon, 12 Oct 2026 10:48:06 +0800 Subject: [PATCH] Bluetooth: MSFT: Serialize handle map cleanup with event processing MSFT monitor handle mappings must remain valid while vendor events look up and use them under hdev->lock. msft_do_close() removes and frees the mappings without that lock. hci_dev_close_sync() clears HCI_UP and drains the RX workqueue before MSFT cleanup. However, a transport callback that already passed hci_recv_frame()'s state check can queue a vendor event after the drain returns, if no earlier shutdown callback has quiesced reception. The driver close callback runs after MSFT cleanup, so event processing can overlap the unlocked removal. msft_monitor_device_evt() can then traverse freed list entries or read handle_data->mgmt_handle after it is freed. Take hdev->lock while resetting monitor states and removing handle mappings in msft_do_close(), as normal monitor cancellation already does. An active event reader then finishes before its mapping is freed, and later lookups see an empty handle map. An instrumented kernel produced this KASAN report (timestamps removed and unrelated frames omitted): BUG: KASAN: slab-use-after-free in msft_vendor_evt+0x1906/0x1990 Read of size 2 at addr ffff888104df3602 by task kworker/u17:2/502 Workqueue: hci0 hci_rx_work Call Trace: [...] msft_vendor_evt+0x1906/0x1990 hci_vendor_evt+0x6f/0x90 hci_event_packet+0x894/0xc70 [...] hci_rx_work+0x3f8/0xfa0 [...] Allocated by task 499: [...] msft_add_monitor_sync+0x6a8/0x10a0 msft_add_monitor_pattern+0x7f/0xb0 hci_add_adv_monitor+0x1fa/0x2e0 [...] Freed by task 499: [...] kfree+0x307/0x580 msft_do_close+0x238/0x750 hci_dev_close_sync+0x546/0x1380 [...] The buggy address belongs to the object at ffff888104df3600 which belongs to the cache kmalloc-32 of size 32 The buggy address is located 2 bytes inside of freed 32-byte region [ffff888104df3600, ffff888104df3620) [...] Fixes: 145373cb1b1f ("Bluetooth: Add framework for Microsoft vendor extension") Assisted-by: LLM Signed-off-by: Cen Zhang Signed-off-by: Luiz Augusto von Dentz --- net/bluetooth/msft.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/net/bluetooth/msft.c b/net/bluetooth/msft.c index 6f4b7c38a247..2559c5b1bef0 100644 --- a/net/bluetooth/msft.c +++ b/net/bluetooth/msft.c @@ -683,6 +683,8 @@ void msft_do_close(struct hci_dev *hdev) bt_dev_dbg(hdev, "Cleanup of MSFT extension"); + hci_dev_lock(hdev); + /* The controller will silently remove all monitors on power off. * Therefore, remove handle_data mapping and reset monitor state. */ @@ -697,6 +699,8 @@ void msft_do_close(struct hci_dev *hdev) kfree(handle_data); } + hci_dev_unlock(hdev); + mutex_lock(&msft->filter_lock); list_for_each_entry_safe(address_filter, n, &msft->address_filters, list) {