CVE-2026-63902

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

USB: serial: cypress_m8: validate interrupt packet headers

cypressreadintcallback() 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 URBSHORTNOTOK 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 cypressreadintcallback+0x240/0x7f0 Read of size 1 Call trace: cypressreadintcallback() (drivers/usb/serial/cypress_m8.c:1009) __usbhcdgivebackurb() dummytimer()

[ johan: use constants in header length sanity checks ]