CVE-2026-64453 — usb: misc: usbio: fix disconnect UAF in client teardown

Affected: Linux

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

usb: misc: usbio: fix disconnect UAF in client teardown

usbio_disconnect() walks usbio->cli_list in reverse and uninitializes each auxiliary device. auxiliary_device_uninit() drops the device reference, and for an unbound child that can run usbio_auxdev_release() and free the containing struct usbio_client.

list_for_each_entry_reverse() advances after the loop body by reading client->link.prev. If the current client is freed by auxiliary_device_uninit(), the iterator dereferences freed memory.

Use list_for_each_entry_safe_reverse() so the previous client is cached before the body can drop the final reference. This preserves reverse teardown order while keeping the next iterator cursor independent of the current client's lifetime.

Validation reproduced this kernel report: BUG: KASAN: slab-use-after-free in usbio_disconnect+0x12e/0x150

Call Trace: <TASK> dump_stack_lvl+0x66/0xa0 print_report+0xce/0x630 ? usbio_disconnect+0x12e/0x150 ? srso_alias_return_thunk+0x5/0xfbef5 ? __virt_addr_valid+0x188/0x320 ? usbio_disconnect+0x12e/0x150 kasan_report+0xe0/0x110 ? usbio_disconnect+0x12e/0x150 usbio_disconnect+0x12e/0x150 usb_unbind_interface+0xf3/0x400 really_probe+0x316/0x660 __driver_probe_device+0x106/0x240 driver_probe_device+0x4a/0x110 __device_attach_driver+0xf1/0x1a0 ? __pfx___device_attach_driver+0x10/0x10 bus_for_each_drv+0xf9/0x160 ? __pfx_bus_for_each_drv+0x10/0x10 ? srso_alias_ret…

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CVE-2026-64453 — usb: misc: usbio: fix disconnect UAF in client teardown