CVE-2026-64357

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

xfs: fix exchmaps reservation limit check

xfsexchmapsestimateoverhead() adds the bmbt and rmapbt overhead to a local resblks variable, but the final UINTMAX check still tests req->resblks. That is the reservation value from before the overhead was added.

The computed value is stored back in req->resblks and later passed to xfstransalloc(), whose block reservation argument is unsigned int. Check the computed reservation so the existing limit applies to the value that will be used.