CVE-2026-72310: smb: client: fix overflow in passthrough ioctl bounds check

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

smb: client: fix overflow in passthrough ioctl bounds check

smb2ioctlqueryinfo() validates the PASSTHRUFSCTL response payload before copying it to userspace.

The payload offset and length both come from 32-bit fields. The bounds check currently adds OutputOffset and qi.inputbufferlength directly, so the addition can wrap in 32-bit arithmetic before the result is compared against the response buffer length.

A malicious server can use a large OutputOffset and a small OutputCount to make the wrapped sum pass the bounds check. The later copytouser() then reads from iorsp + OutputOffset, outside the response buffer.

Use sizeadd() for the offset plus length check so overflow is treated as out of bounds.