This is a note to let you know that I've just added the patch titled cdc-acm: Add DISABLE_ECHO quirk for Microchip/SMSC chip to the 4.19-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: cdc-acm-add-disable_echo-quirk-for-microchip-smsc-chip.patch and it can be found in the queue-4.19 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From 03894573f2913181ee5aae0089f333b2131f2d4b Mon Sep 17 00:00:00 2001 From: Joakim Tjernlund <joakim.tjernlund@xxxxxxxxxxxx> Date: Fri, 5 Jun 2020 12:54:18 +0200 Subject: cdc-acm: Add DISABLE_ECHO quirk for Microchip/SMSC chip From: Joakim Tjernlund <joakim.tjernlund@xxxxxxxxxxxx> commit 03894573f2913181ee5aae0089f333b2131f2d4b upstream. USB_DEVICE(0x0424, 0x274e) can send data before cdc_acm is ready, causing garbage chars on the TTY causing stray input to the shell and/or login prompt. Signed-off-by: Joakim Tjernlund <joakim.tjernlund@xxxxxxxxxxxx> Cc: stable@xxxxxxxxxxxxxxx Acked-by: Oliver Neukum <oneukum@xxxxxxxx> Link: https://lore.kernel.org/r/20200605105418.22263-1-joakim.tjernlund@xxxxxxxxxxxx Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- drivers/usb/class/cdc-acm.c | 2 ++ 1 file changed, 2 insertions(+) --- a/drivers/usb/class/cdc-acm.c +++ b/drivers/usb/class/cdc-acm.c @@ -1721,6 +1721,8 @@ static int acm_pre_reset(struct usb_inte static const struct usb_device_id acm_ids[] = { /* quirky and broken devices */ + { USB_DEVICE(0x0424, 0x274e), /* Microchip Technology, Inc. (formerly SMSC) */ + .driver_info = DISABLE_ECHO, }, /* DISABLE ECHO in termios flag */ { USB_DEVICE(0x076d, 0x0006), /* Denso Cradle CU-321 */ .driver_info = NO_UNION_NORMAL, },/* has no union descriptor */ { USB_DEVICE(0x17ef, 0x7000), /* Lenovo USB modem */ Patches currently in stable-queue which might be from joakim.tjernlund@xxxxxxxxxxxx are queue-4.19/cdc-acm-add-disable_echo-quirk-for-microchip-smsc-chip.patch