Re: MAX3420 UDC: out-of-bounds read/write via unvalidated wIndex in USB SETUP packet

Greg KH
2026-04-12T05:05:42Z

On Sat, Apr 11, 2026 at 11:28:08PM +0530, Pavitra Jha wrote:
> Hello,
>
> I am reporting an out-of-bounds read and write in the MAX3420 USB
> Device Controller driver. The issue arises from using a
> host-controlled wIndex field from a USB SETUP packet as a direct index
> into a fixed-size endpoint array without validating that the index is
> within bounds.
>
> The driver handles USB control requests originating from an external
> USB host and therefore must treat all request fields as untrusted.

Did you look in the mailing list archives for this driver? This has
been discussed in the past, most recently:
https://lore.kernel.org/r/20260121203944.1898-2-qikeyu2017@gmail.com

Please get this hardware and validate that this even actually can
happen, as last time around, it was stated that it could not due to how
the hardware worked. If that is incorrect, we'll be glad to take the
change, but that needs to actually be tested, not just attempted with a
fake device in qemu.

thanks,

greg k-h