CVE-2026-89723

Status: UPDATED  |  Advisory ID: CVE-2026-89723

Key Details

Affected Products, Subsystems & Sectors

What to Know

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

nilfs2: fix slab-out-of-bounds in nilfs_direct_propagate after truncation

Shuangpeng Bai reported that KASAN detected a slab-out-of-bounds error

in nilfs_direct_propagate() during testing.

Analysis revealed that after truncating a file, a node block immediately

below the B-tree root was not deleted. Instead, it remained in the B-tree

node cache in a dirty state. The log writer subsequently detected this

block and incorrectly invoked nilfs_direct_propagate() on it, which is

designed to handle only data blocks in direct mapping.

B-tree nodes in the cache are managed by virtual block numbers, and their

logical keys typically exceed the range expected by direct mapping.

Consequently, processing such a node as a direct mapping entry triggers

a slab-out-of-bounds access.

The root cause is that when a B-tree mapping collapses into a direct

mapping during truncation, an intermediate node block pointed to by the

root node is left behind as garbage instead of being explicitly deleted.

This resolves the issue by adding a nilfs_btree_discard() operation

to delete the remaining intermediate node block during the conversion.

A 'deform' flag is added to the bop_delete interface to explicitly signal

that the deletion is part of a mapping transformation. This allows the

B-tree mapping implementation to perform the necessary cleanup and

discarding of the residual node structure that would be otherwise be left

orphaned after the transition. (NVD)

What to Do

Monitor Linux's web page for any future patch releases.

References