[PATCH v2 00/11] USB: new USB control message helper functions

Greg Kroah-Hartman
2020-09-07T14:57:45Z

In a recent discussion about a USB networking bug found by syzbot, and
fixed by Himadri Pandya, the design of the existing usb_control_msg()
call was brought up as not being the "nicest" thing to use by Dmitry
Vyukov:
https://lore.kernel.org/r/CACT4Y+YbDODLRFn8M5QcY4CazhpeCaunJnP_udXtAs0rYoASSg@mail.gmail.com

The function makes it hard to get right, in that it will return the
number of bytes sent/received, but almost no one checks to see if a
short read/write happens. With a malicious, or broken, USB device, this
can cause drivers to act on data that they did not anticipate, and
sometimes copy internal kernel data out to userspace.

So let's fix this up by creating two new functions,
usb_control_msg_send() and usb_control_msg_recv(). These functions
either complete the full transation, or they return an error, a short
send/recv is now an error.

They also accept data off of the stack, saving individual drivers the
pain of having to constantly allocate memory on their own for tiny
messages, thereby saving overall kernel code space.

The api also does not require a raw USB "pipe" to be sent to the
function, as we know the direction, so just pass in the endpoint number
instead, again making it easier on the USB driver author to use.

This series first takes a helper function out of the sound core for
verifying USB endpoints to be able to use internally, and then adds the
new functions, converts over some internal USB code to use them, and
then starts to clean up some drivers using these new functions, as an
example of the savings that can happen by using these functions.

Thanks to Dmitry and Himadri for the idea on how to do all of this.

greg k-h

Changes from v1:
- added acks from Takashi Iwai
- dropped changes to one function in patch 04 thanks to review
from Alan Stern
- typo fix in comment in patch 01
- added new patch 11 to remove some unneeded checks in the sound
drivers for endpoint statuses that would always be true.

*** BLURB HERE ***

Greg Kroah-Hartman (11):
USB: move snd_usb_pipe_sanity_check into the USB core
USB: add usb_control_msg_send() and usb_control_msg_recv()
USB: core: message.c: use usb_control_msg_send() in a few places
USB: core: hub.c: use usb_control_msg_send() in a few places
USB: legousbtower: use usb_control_msg_recv()
sound: usx2y: move to use usb_control_msg_send()
sound: 6fire: move to use usb_control_msg_send() and
usb_control_msg_recv()
sound: line6: move to use usb_control_msg_send() and
usb_control_msg_recv()
sound: hiface: move to use usb_control_msg_send()
Bluetooth: ath3k: use usb_control_msg_send() and
usb_control_msg_recv()
ALSA: remove calls to usb_pipe_type_check for control endpoints

drivers/bluetooth/ath3k.c | 90 +++++------------
drivers/usb/core/hub.c | 99 ++++++++----------
drivers/usb/core/message.c | 171 ++++++++++++++++++++++++++++----
drivers/usb/core/urb.c | 31 ++++--
drivers/usb/misc/legousbtower.c | 60 ++++-------
include/linux/usb.h | 7 ++
sound/usb/6fire/firmware.c | 38 +++----
sound/usb/helper.c | 16 +--
sound/usb/helper.h | 1 -
sound/usb/hiface/pcm.c | 14 ++-
sound/usb/line6/driver.c | 69 +++++--------
sound/usb/line6/podhd.c | 17 ++--
sound/usb/line6/toneport.c | 8 +-
sound/usb/mixer_scarlett_gen2.c | 2 +-
sound/usb/quirks.c | 12 +--
sound/usb/usx2y/us122l.c | 42 ++------
16 files changed, 335 insertions(+), 342 deletions(-)

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2.28.0