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tty: n_gsm: fix missing explicit ldisc flush

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commit 17eac652028501df7ea296b1d9b9c134db262b7d upstream.

In gsm_cleanup_mux() the muxer is closed down and all queues are removed.
However, removing the queues is done without explicit control of the
underlying buffers. Flush those before freeing up our queues to ensure
that all outgoing queues are cleared consistently. Otherwise, a new mux
connection establishment attempt may time out while the underlying tty is
still busy sending out the remaining data from the previous connection.

Fixes: e1eaea46bb40 ("tty: n_gsm line discipline")
Cc: stable@vger.kernel.org
Signed-off-by: Daniel Starke <daniel.starke@siemens.com>
Link: https://lore.kernel.org/r/20220414094225.4527-10-daniel.starke@siemens.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Daniel Starke 2022-04-14 02:42:15 -07:00 committed by Greg Kroah-Hartman
parent a2baa907c2
commit 17b86db43c
1 changed files with 1 additions and 0 deletions
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drivers/tty/n_gsm.c
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@ -2079,6 +2079,7 @@ static void gsm_cleanup_mux(struct gsm_mux *gsm, bool disc)
gsm_dlci_release(gsm->dlci[i]);
mutex_unlock(&gsm->mutex);
/* Now wipe the queues */
tty_ldisc_flush(gsm->tty);
list_for_each_entry_safe(txq, ntxq, &gsm->tx_list, list)
kfree(txq);
INIT_LIST_HEAD(&gsm->tx_list);