CVE-2026-89458

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

s390/dasd: Do not complete a failed ESE read as successful

dasd int handler() completes an NRF read of an unallocated ESE track by calling ese read() and unconditionally marking the request DASD CQR SUCCESS. dasd eckd ese read() can return an error before it has zeroed the destination buffer: a failed sense-data parse or a current track outside the requested range both return early, leaving the destination pages untouched. The request is still completed successfully, so the block layer is handed stale / uninitialized memory instead of zeros.

Check the ese read() return value and fail the request through the normal error path instead of forcing DASD CQR SUCCESS.