CVE-2026-45858 ext4: don't zero the entire extent if EXT4_EXT_DATA_PARTIAL_VALID1

In the Linux kernel, the following vulnerability has been resolved: ext4: don't zero the entire extent if EXT4EXTDATAPARTIALVALID1 When allocating initialized blocks from a large unwritten extent, or when splitting an unwritten extent during end I/O and converting it to initialized, there is...