This is a note to let you know that I've just added the patch titled USB: serial: ftdi_sio: fix line-status over-reporting to the 4.4-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: usb-serial-ftdi_sio-fix-line-status-over-reporting.patch and it can be found in the queue-4.4 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From a6bb1e17a39818b01b55d8e6238b4b5f06d55038 Mon Sep 17 00:00:00 2001 From: Johan Hovold <johan@xxxxxxxxxx> Date: Thu, 2 Feb 2017 17:38:35 +0100 Subject: USB: serial: ftdi_sio: fix line-status over-reporting From: Johan Hovold <johan@xxxxxxxxxx> commit a6bb1e17a39818b01b55d8e6238b4b5f06d55038 upstream. FTDI devices use a receive latency timer to periodically empty the receive buffer and report modem and line status (also when the buffer is empty). When a break or error condition is detected the corresponding status flags will be set on a packet with nonzero data payload and the flags are not updated until the break is over or further characters are received. In order to avoid over-reporting break and error conditions, these flags must therefore only be processed for packets with payload. This specifically fixes the case where after an overrun, the error condition is continuously reported and NULL-characters inserted until further data is received. Reported-by: Michael Walle <michael@xxxxxxxx> Fixes: 72fda3ca6fc1 ("USB: serial: ftd_sio: implement sysrq handling on break") Fixes: 166ceb690750 ("USB: ftdi_sio: clean up line-status handling") Signed-off-by: Johan Hovold <johan@xxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- drivers/usb/serial/ftdi_sio.c | 23 ++++++++++++++--------- 1 file changed, 14 insertions(+), 9 deletions(-) --- a/drivers/usb/serial/ftdi_sio.c +++ b/drivers/usb/serial/ftdi_sio.c @@ -2070,6 +2070,20 @@ static int ftdi_process_packet(struct us priv->prev_status = status; } + /* save if the transmitter is empty or not */ + if (packet[1] & FTDI_RS_TEMT) + priv->transmit_empty = 1; + else + priv->transmit_empty = 0; + + len -= 2; + if (!len) + return 0; /* status only */ + + /* + * Break and error status must only be processed for packets with + * data payload to avoid over-reporting. + */ flag = TTY_NORMAL; if (packet[1] & FTDI_RS_ERR_MASK) { /* Break takes precedence over parity, which takes precedence @@ -2092,15 +2106,6 @@ static int ftdi_process_packet(struct us } } - /* save if the transmitter is empty or not */ - if (packet[1] & FTDI_RS_TEMT) - priv->transmit_empty = 1; - else - priv->transmit_empty = 0; - - len -= 2; - if (!len) - return 0; /* status only */ port->icount.rx += len; ch = packet + 2; Patches currently in stable-queue which might be from johan@xxxxxxxxxx are queue-4.4/usb-serial-ftdi_sio-fix-modem-status-error-handling.patch queue-4.4/usb-serial-cp210x-add-new-ids-for-ge-bx50v3-boards.patch queue-4.4/usb-serial-ark3116-fix-register-accessor-error-handling.patch queue-4.4/usb-serial-digi_acceleport-fix-oob-data-sanity-check.patch queue-4.4/usb-serial-ftdi_sio-fix-line-status-over-reporting.patch queue-4.4/usb-serial-ftdi_sio-fix-extreme-low-latency-setting.patch queue-4.4/usb-serial-spcp8x5-fix-modem-status-handling.patch queue-4.4/usb-serial-opticon-fix-cts-retrieval-at-open.patch queue-4.4/usb-serial-mos7840-fix-another-null-deref-at-open.patch