جزئیات آسیب‌پذیری

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.

• https://git.kernel.org/stable/c/3f075832734005310740d148d1cf1c1e792ebdca
• https://git.kernel.org/stable/c/588ccd19a6e69eca72d54608c3ab3b45709b2305
• https://git.kernel.org/stable/c/cf646a9f5554bc07d6ccb59c327812b3a0c6a368
• https://git.kernel.org/stable/c/9030a1bbe2c6b1e3e54cef462d159b5248f09fd2
• https://git.kernel.org/stable/c/bfdf412208fea7fc0d5b32d68a35b25261917393
• https://git.kernel.org/stable/c/ba4c776af3dc21ed04e315e6545e99703bb1b53a
• https://git.kernel.org/stable/c/ee08414d78b851e3d1856d6e4d631939b01a1bbe
• https://git.kernel.org/stable/c/8265a626cc14a48e46e6dc8c47667e72b4232ac2