CVE-2026-98651

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

KVM: s390: Properly handle NULL pointer in dat_cond_set_storage_key()

Some callers pass NULL as oldkey. Calling page_cond_set_storage_key() will cause that NULL pointer to get dereferenced.

Fix by checking for NULL and assigning the pointer to a dummy local variable to avoid crashes.