CVE-2026-45877: HID: intel-ish-hid: fix NULL-ptr-deref in ishtp_bus_remove_all_clients

In the Linux kernel, the following vulnerability has been resolved: HID: intel-ish-hid: fix NULL-ptr-deref in ishtp_bus_remove_all_clients During a warm reset flow, the cl->device pointer may be NULL if the reset occurs while clients are still being enumerated. Accessing cl->device->reference_count without a NULL check leads to a kernel panic. This issue was identified during multi-unit warm reboot stress clycles. Add a defensive NULL check for cl->device to ensure stability under such intensive testing conditions. KASAN: null-ptr-deref in range [0000000000000000-0000000000000007] Workqueue: ish_fw_update_wq fw_reset_work_fn Call Trace: ishtp_bus_remove_all_clients+0xbe/0x130 [intel_ishtp] ishtp_reset_handler+0x85/0x1a0 [intel_ishtp] fw_reset_work_fn+0x8a/0xc0 [intel_ish_ipc]