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

Squashfs: fix uninit-value in squashfs_get_parent

Syzkaller reports a "KMSAN: uninit-value in squashfs_get_parent" bug.

This is caused by open_by_handle_at() being called with a file handle
containing an invalid parent inode number. In particular the inode number
is that of a symbolic link, rather than a directory.

Squashfs_get_parent() gets called with that symbolic link inode, and
accesses the parent member field.

unsigned int parent_ino = squashfs_i(inode)->parent;

Because non-directory inodes in Squashfs do not have a parent value, this
is uninitialised, and this causes an uninitialised value access.

The fix is to initialise parent with the invalid inode 0, which will cause
an EINVAL error to be returned.

Regular inodes used to share the parent field with the block_list_start
field. This is removed in this commit to enable the parent field to
contain the invalid inode number 0.
Advisories

No advisories yet.

Fixes

Solution

No solution given by the vendor.


Workaround

No workaround given by the vendor.

History

Tue, 28 Oct 2025 12:00:00 +0000

Type Values Removed Values Added
Description In the Linux kernel, the following vulnerability has been resolved: Squashfs: fix uninit-value in squashfs_get_parent Syzkaller reports a "KMSAN: uninit-value in squashfs_get_parent" bug. This is caused by open_by_handle_at() being called with a file handle containing an invalid parent inode number. In particular the inode number is that of a symbolic link, rather than a directory. Squashfs_get_parent() gets called with that symbolic link inode, and accesses the parent member field. unsigned int parent_ino = squashfs_i(inode)->parent; Because non-directory inodes in Squashfs do not have a parent value, this is uninitialised, and this causes an uninitialised value access. The fix is to initialise parent with the invalid inode 0, which will cause an EINVAL error to be returned. Regular inodes used to share the parent field with the block_list_start field. This is removed in this commit to enable the parent field to contain the invalid inode number 0.
Title Squashfs: fix uninit-value in squashfs_get_parent
References

cve-icon MITRE

Status: PUBLISHED

Assigner: Linux

Published:

Updated: 2025-10-28T11:48:25.862Z

Reserved: 2025-04-16T07:20:57.157Z

Link: CVE-2025-40049

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Received

Published: 2025-10-28T12:15:39.043

Modified: 2025-10-28T12:15:39.043

Link: CVE-2025-40049

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

No data.