CVE-2026-31449

In the Linux kernel, the following vulnerability has been resolved:<br /> <br /> ext4: validate p_idx bounds in ext4_ext_correct_indexes<br /> <br /> ext4_ext_correct_indexes() walks up the extent tree correcting<br /> index entries when the first extent in a leaf is modified. Before<br /> accessing path[k].p_idx-&gt;ei_block, there is no validation that<br /> p_idx falls within the valid range of index entries for that<br /> level.<br /> <br /> If the on-disk extent header contains a corrupted or crafted<br /> eh_entries value, p_idx can point past the end of the allocated<br /> buffer, causing a slab-out-of-bounds read.<br /> <br /> Fix this by validating path[k].p_idx against EXT_LAST_INDEX() at<br /> both access sites: before the while loop and inside it. Return<br /> -EFSCORRUPTED if the index pointer is out of range, consistent<br /> with how other bounds violations are handled in the ext4 extent<br /> tree code.