CVE-2026-45981

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

s390/cio: Fix device lifecycle handling in css_alloc_subchannel()

css_alloc_subchannel() calls device_initialize() before setting up the DMA masks. If dma_set_coherent_mask() or dma_set_mask() fails, the error path frees the subchannel structure directly, bypassing the device model reference counting.

Once device_initialize() has been called, the embedded struct device must be released via put_device(), allowing the release callback to free the container structure.

Fix the error path by dropping the initial device reference with put_device() instead of calling kfree() directly.

This ensures correct device lifetime handling and avoids potential use-after-free or double-free issues.