nfc: nci: fix double completion race in nci_data_exchange_complete

In the Linux kernel, the following vulnerability has been resolved: nfc: nci: fix double completion race in nci_data_exchange_complete nci_close_device() and nci_rx_work can both call nci_data_exchange_complete() concurrently. After commit 4527025d440ce8 ("nfc: nci: fix circular locking dependency in nci_close_device") moved flush_workqueue(ndev->rx_wq) after mutex_unlock(&ndev->req_lock), rx_work is no longer serialized with the explicit completion call in the close path. Both callers read the non-NULL callback pointer and invoke rawsock_data_exchange_complete(), which calls sock_put() -- but only one sock_hold() was taken, so the second sock_put() underflows the refcount and frees the socket while it is still in use. Replace the bare clear_bit(NCI_DATA_EXCHANGE) with test_and_clear_bit() so that only the first caller proceeds to invoke the callback.

Source published

17 Sep 2026 16:07:34 UTC

Source modified

19 Oct 2026 09:00:00 UTC

Observed here

23 Oct 2026 15:48:27 UTC

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CVSS 3.1 · 7.5 CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H