This is a note to let you know that I've just added the patch titled

serdev: fix receive_buf return value when no callback

to the 4.14-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git%3Ba=su...

The filename of the patch is: serdev-fix-receive_buf-return-value-when-no-callback.patch and it can be found in the queue-4.14 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let stable@vger.kernel.org know about it.

From foo@baz Fri Feb 23 11:45:09 CET 2018

From: Johan Hovold johan@kernel.org Date: Fri, 3 Nov 2017 15:30:53 +0100 Subject: serdev: fix receive_buf return value when no callback

From: Johan Hovold johan@kernel.org

[ Upstream commit fd00cf81a9a84776ba58e56bd042c726dcf75cf3 ]

The receive_buf callback is supposed to return the number of bytes processed and should specifically not return a negative errno.

Due to missing sanity checks in the serdev tty-port controller, a driver not providing a receive_buf callback could cause the flush_to_ldisc() worker to spin in a tight loop when the tty buffer pointers are incremented with -EINVAL (-22).

The missing sanity checks have now been added to the tty-port controller, but let's fix up the serdev-controller helper as well.

Signed-off-by: Johan Hovold johan@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org Signed-off-by: Sasha Levin alexander.levin@verizon.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- include/linux/serdev.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/include/linux/serdev.h +++ b/include/linux/serdev.h @@ -184,7 +184,7 @@ static inline int serdev_controller_rece struct serdev_device *serdev = ctrl->serdev;

if (!serdev || !serdev->ops->receive_buf) - return -EINVAL; + return 0;

return serdev->ops->receive_buf(serdev, data, count); }

Patches currently in stable-queue which might be from johan@kernel.org are

queue-4.14/serdev-fix-receive_buf-return-value-when-no-callback.patch