CVE-2026-93798

About vulnerability

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

btrfs: fix reloc root cleanup in merge_reloc_roots()

If the root we got has zero root refs in its root item, we are resetting the root’s ->reloc_root without using barriers like we do everywhere else. Sashiko complained about this while reviewing another patch, and it’s correct (see the Link tag below).

Also, we should not clear BTRFS_ROOT_DEAD_RELOC_TREE from the root unless the root points to the reloc root we have.

Fix this by using clear_reloc_root(), which issues the memory barrier after setting the root’s ->reloc_root to NULL and before clearing the bit BTRFS_ROOT_DEAD_RELOC_TREE from the root.

Affected product:

AlmaLinux 9.2 ESU , Amazon Linux 2 ELS , Debian 10 ELS , Debian 11 ELS , TuxCare 9.6 ESU , TuxCare 9.8 ESU , Ubuntu 16.04 ELS , Ubuntu 18.04 ELS , Ubuntu 20.04 ELS

Affected packages:

linux @ 5.4.0 (+8 more)

Live-patch status from KernelCare for each operating system.