CVE-2026-31449 ext4: validate p_idx bounds in ext4_ext_correct_indexes

In the Linux kernel, the following vulnerability has been resolved: ext4: validate pidx bounds in ext4extcorrectindexes ext4extcorrectindexes walks up the extent tree correcting index entries when the first extent in a leaf is modified. Before accessing pathk.pidx-eiblock, there is no validation...