CVE-2026-97548: xfs: fix the rtrmap and rtrefcount _maxlevels_ondisk functions
In the Linux kernel, the following vulnerability has been resolved:
xfs: fix the rtrmap and rtrefcount maxlevelsondisk functions
The maxlevelsondisk functions are used to compute the size of in-memory btree cursors for each btree type. Unfortunately, LOLLM noticed that the rtrmap and rtrefcount versions of these functions forget to account for the inode root, which means that we could access beyond the end of the cursor given a sufficiently large btree. Fix this.
Affected Software
Event History
Frequently Asked Questions
Which systems are exposed to this issue?
Linux kernel systems using XFS are relevant, but the out-of-bounds cursor access requires a sufficiently large realtime reverse-mapping or realtime reference-count btree. The affected code paths are the rtrmap and rtrefcount btree cursor sizing functions.
What condition is required to trigger the out-of-bounds access?
The relevant realtime btree must be sufficiently large. The flawed maximum-level calculation omits the inode root, causing the allocated in-memory btree cursor to be too small for that condition.
How can administrators determine whether their filesystem may be affected?
Assess whether affected XFS filesystems use realtime reverse mapping or realtime reference counting and have sufficiently large associated btrees. The supplied information does not provide a version-based detection method or a configuration-independent indicator.