CVE-2026-89793 ublk: clear VM_MAYWRITE on read-only ublk char device mmap

In the Linux kernel, the following vulnerability has been resolved: ublk: clear VMMAYWRITE on read-only ublk char device mmap ublkchmmap rejects mmap requests with VMWRITE set, but never clears VMMAYWRITE on the resulting read-only mapping. This allows a userspace daemon to mmap the per-queue...