USB: serial: cypress_m8: validate interrupt packet headers

In the Linux kernel, the following vulnerability has been resolved:

USB: serial: cypress_m8: validate interrupt packet headers

cypress_read_int_callback() parses the interrupt-in buffer according to

the selected Cypress packet format. Format 1 has a two-byte status/count

header and format 2 has a one-byte combined status/count header. The

usb-serial core sizes the interrupt-in buffer from the endpoint

descriptor's wMaxPacketSize, and successful interrupt transfers can

complete short when URB_SHORT_NOT_OK is not set.

Check that the completed packet contains the selected header before

reading it. Malformed short reports are ignored and the interrupt URB is

resubmitted through the existing retry path, preventing out-of-bounds

header-byte reads.

KASAN report as below:

KASAN slab-out-of-bounds in cypress_read_int_callback+0x240/0x7f0

Read of size 1

Call trace:

cypress_read_int_callback() (drivers/usb/serial/cypress_m8.c:1009)

__usb_hcd_giveback_urb()

dummy_timer()

[ johan: use constants in header length sanity checks ]