In the Linux kernel, the following vulnerability has been resolved: xfs: don't let hidden_space go negative in xfs_metafile_resv_init LOLLM points… (CVE-2026-98446)

The vulnerability in the Linux kernel's XFS filesystem involves an integer underflow in the hidden_space variable during the initialization of metadata file reservations (xfs_metafile_resv_init). Specifically, if the amount of fdblocks reserved is less than the space already used by the metadata btree file, the subtraction operation underflows, causing xfs_dec_fdblocks to subtract an excessively large amount of space. This flaw could lead to incorrect filesystem metadata accounting. The fix involves adjusting the logic to ensure the target reservation does not fall below the used space, preventing the underflow. An adjacent comment error was also corrected.

The impact is an incorrect accounting of filesystem metadata space due to an integer underflow, which could potentially lead to filesystem inconsistencies or corruption. No specific exploitation details or active exploits are reported.

A fix has been implemented in the Linux kernel to correct the logic in xfs_metafile_resv_init, preventing the hidden_space variable from going negative. Users should update to the fixed kernel version once available. No additional mitigation steps are indicated.