diff options
| author | Jakub Kicinski <kuba@kernel.org> | 2026-03-17 12:33:34 -0700 |
|---|---|---|
| committer | Jakub Kicinski <kuba@kernel.org> | 2026-03-19 16:56:18 -0700 |
| commit | 4527025d440ce84bf56e75ce1df2e84cb8178616 (patch) | |
| tree | 4db6f55aeb815d818046869d809a997a2de74113 /net | |
| parent | 57ce3b2e9cdabcbc4d5a10f0e97a1399058c7417 (diff) | |
nfc: nci: fix circular locking dependency in nci_close_device
nci_close_device() flushes rx_wq and tx_wq while holding req_lock.
This causes a circular locking dependency because nci_rx_work()
running on rx_wq can end up taking req_lock too:
nci_rx_work -> nci_rx_data_packet -> nci_data_exchange_complete
-> __sk_destruct -> rawsock_destruct -> nfc_deactivate_target
-> nci_deactivate_target -> nci_request -> mutex_lock(&ndev->req_lock)
Move the flush of rx_wq after req_lock has been released.
This should safe (I think) because NCI_UP has already been cleared
and the transport is closed, so the work will see it and return
-ENETDOWN.
NIPA has been hitting this running the nci selftest with a debug
kernel on roughly 4% of the runs.
Fixes: 6a2968aaf50c ("NFC: basic NCI protocol implementation")
Reviewed-by: Ian Ray <ian.ray@gehealthcare.com>
Link: https://patch.msgid.link/20260317193334.988609-1-kuba@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Diffstat (limited to 'net')
| -rw-r--r-- | net/nfc/nci/core.c | 10 |
1 files changed, 6 insertions, 4 deletions
diff --git a/net/nfc/nci/core.c b/net/nfc/nci/core.c index 43d871525dbc..5f46c4b5720f 100644 --- a/net/nfc/nci/core.c +++ b/net/nfc/nci/core.c @@ -579,8 +579,7 @@ static int nci_close_device(struct nci_dev *ndev) skb_queue_purge(&ndev->rx_q); skb_queue_purge(&ndev->tx_q); - /* Flush RX and TX wq */ - flush_workqueue(ndev->rx_wq); + /* Flush TX wq, RX wq flush can't be under the lock */ flush_workqueue(ndev->tx_wq); /* Reset device */ @@ -592,13 +591,13 @@ static int nci_close_device(struct nci_dev *ndev) msecs_to_jiffies(NCI_RESET_TIMEOUT)); /* After this point our queues are empty - * and no works are scheduled. + * rx work may be running but will see that NCI_UP was cleared */ ndev->ops->close(ndev); clear_bit(NCI_INIT, &ndev->flags); - /* Flush cmd wq */ + /* Flush cmd and tx wq */ flush_workqueue(ndev->cmd_wq); timer_delete_sync(&ndev->cmd_timer); @@ -613,6 +612,9 @@ static int nci_close_device(struct nci_dev *ndev) mutex_unlock(&ndev->req_lock); + /* rx_work may take req_lock via nci_deactivate_target */ + flush_workqueue(ndev->rx_wq); + return 0; } |