CVE-2026-68145 iomap: fix out-of-bounds bitmap_set() with zero-length range

In the Linux kernel, the following vulnerability has been resolved: iomap: fix out-of-bounds bitmapset with zero-length range ifssetrangedirty and ifssetrangeuptodate compute lastblk as off + len - 1 iblkbits. When off is 0 and len is 0, the unsigned subtraction underflows to SIZEMAX, producing a...