CVE-2026-89640 cifs: fix loff_t underflow in cifs_remap_file_range() when len == 0

In the Linux kernel, the following vulnerability has been resolved: cifs: fix lofft underflow in cifsremapfilerange when len == 0 With len == 0 clone to EOF, the effective length is computed as: len = srcinode-isize - off; If off isize, this is a negative lofft, corrupting the ByteCount in the...