CVE-2026-72188

In the Linux kernel, the following vulnerability has been resolved:

ntfs: sanitize MFT references returned from ntfslookupinodebyname()

ntfslookupinodebyname() returns MFT references read from directory index entries on disk. These values are untrusted, but the function can currently return an error-marked MFT reference to its callers without validating it.

Callers later decode lookup failures with MREF_ERR(). A crafted NTFS image can set the MREF error bit while leaving the low bits as an arbitrary value, causing callers to consume a bogus pseudo-errno instead of treating the lookup result as corrupted on-disk metadata.

Fix this at the source by normalizing every error-marked MFT reference returned from ntfslookupinodebyname() to ERR_MREF(-EIO). Apply this to all four directory lookup return paths so every caller gets a validated result without needing additional checks or an API change.

This keeps the sanitization in the common lookup helper, which is cleaner than duplicating validation in each caller.