Overview
About vulnerability
In the Linux kernel, the following vulnerability has been resolved:
xfs: fix cursor and pointer handling when recovering iunlink buckets
LOLLM pointed out a bug in xlog_recover_iunlink_bucket:
- We don’t null out prev_ip after releasing it, which can lead to UAF problems if the inodegc flush call in the loop fails.
at which point I noticed even more bugs:
-
If the inodegc flush inside the loop fails, we also leak @ip.
-
We set prev_agino to agino having already advanced agino, which results in inodes with i_prev_unlinked set to itself.
-
If we exit the bottom of the loop with prev_ip set, then prev_ip aliases ip and we also set its i_prev_unlinked to itself.
Bugs 3 and 4 introduce loops into the unlinked list, though these loops don’t surface because we immediately flush each unlinked inode after loading it.
Fix all of these issues.
Details
- Affected product:
- AlmaLinux 9.2 ESU , TuxCare 9.6 ESU , TuxCare 9.8 ESU
- Affected packages:
- kernel @ 5.14.0 (+2 more)
Fixes
KernelCare state
Live-patch status from KernelCare for each operating system.
| Operating system | Status | Covered kernels |
|---|---|---|
| AlmaLinux 9.6 ESU | Planned | — |
| Ubuntu 26.04 | Planned | — |