CVE-2026-68344: usb: atm: ueagle-atm: reject descriptors that confuse probe and disconnect

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

usb: atm: ueagle-atm: reject descriptors that confuse probe and disconnect

ueaprobe() distinguishes a pre-firmware device from a post-firmware one using the USB id (UEAISPREFIRM()), and stores a different object as the interface data in each case: a 'struct completion' for a pre-firmware device (to be waited on in .disconnect()), or a 'struct usbatmdata' for a post-firmware one.

ueadisconnect() instead tells the two apart by the number of interfaces of the active configuration (a pre-firmware device exposes a single interface, ADI930 has 2 and eagle has 3), and casts the interface data accordingly.

Because the two handlers use different criteria, a crafted device that advertises a pre-firmware id together with a multi-interface descriptor (or a post-firmware id with a single interface) makes them disagree: the small 'struct completion' stored by ueaprobe() is then passed to usbatmusbdisconnect(), which casts it to 'struct usbatmdata' and takes instance->serialize, reading past the end of the allocation:

BUG: KASAN: slab-out-of-bounds in mutexlock+0x152a/0x1b80 Read of size 8 at addr ffff8880470e2c60 by task kworker/1:2/982 ... mutexlock+0x152a/0x1b80 usbatmusbdisconnect+0x70/0x820 ueadisconnect+0x133/0x2c0 usbunbindinterface+0x1dd/0x9e0 ... which belongs to the cache kmalloc-96 of size 96 The buggy address is located 0 bytes to the right of allocated 96-byte region [ffff8880470e2c00, ffff8880470e2c60)

Reject such inconsistent descriptors in ueaprobe() so that both handlers always make the same pre/post-firmware decision.