DEBIAN-CVE-2026-89768

See a problem?
Please try reporting it to the source first.

Source

https://security-tracker.debian.org/tracker/CVE-2026-89768

Import Source

https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2026-89768.json

JSON Data

https://api.osv.dev/v1/vulns/DEBIAN-CVE-2026-89768

Upstream

CVE-2026-89768

Published

2026-09-11T20:20:08Z

Modified

2026-09-12T09:00:53Z

Summary

[none]

Details

In the Linux kernel, the following vulnerability has been resolved: fs: fix user path of nested backing files backing_file_open() derives the path to be stored in the new backing file from user_file->f_path. This is incorrect when user_file itself is a backing file, which is the case for nested stacking filesystems, e.g. overlayfs mounts where the lowerdir of one overlayfs is the merged directory of another. Since commit def3ae83da02 ("fs: store real path instead of fake path in backing file f_path") the f_path of a backing file holds the real path of the intermediate layer, not the path that the user opened. Commit 924577e4f6ca ("ovl: Fix nested backing file paths") fixed this for such configurations by passing file_user_path() from ovl_open_realfile(). However, commit 6af36aeb147a ("lsm: add backing_file LSM hooks") changed the first argument of backing_file_open() from the user path back to the user file and derived the path from user_file->f_path again, silently re-introducing the problem. As a result, files mapped through a nested overlayfs show the wrong path in /proc//maps and in perf/ftrace mmap records. For example, with two nested overlayfs mounts: mkdir -p /ovl/{lower,upper,work,merged} /ovl/nested echo hello > /ovl/lower/foo mount -t overlay overlay \ -o lowerdir=/ovl/lower,upperdir=/ovl/upper,workdir=/ovl/work \ /ovl/merged # at least two lowerdirs are needed when upperdir is nonexistent mount -t overlay overlay \ -o lowerdir=/ovl/merged:/ovl/lower /ovl/nested mapping /ovl/nested/foo shows a disconnected path instead of the user path: # readlink /proc/self/fd/3 /ovl/nested/foo # grep foo /proc/self/maps 7f6e2c100000-7f6e2c101000 r--s 00000000 00:24 15813027 /foo The bogus path is derived from the f_path of the intermediate backing file, whose mount is a private clone that d_path() cannot resolve. Fix this by using file_user_path(), which returns the outermost user-visible path for backing files and falls back to &user_file->f_path for regular files. This restores the behavior of commit 924577e4f6ca ("ovl: Fix nested backing file paths") for overlayfs and also fixes the same problem for the other backing_file_open() callers, fuse passthrough and erofs ishare, when their user file is itself a backing file. backing_tmpfile_open() has the same pattern but is not affected: it is only called by ovl_create_tmpfile() for the upper layer, and another overlayfs is rejected as upperdir by the DCACHE_OP_REAL check in ovl_mount_dir_check(), so its user_file can never be a backing file.

References

https://security-tracker.debian.org/tracker/CVE-2026-89768

Affected packages

Debian:13 / linux

Package

Name: linux
Purl: pkg:deb/debian/linux?arch=source&distro=trixie

Affected ranges

Type: ECOSYSTEM
Events: Introduced

0 Unknown introduced version / All previous versions are affected

Affected versions

6.*

6.12.38-1

6.12.41-1

6.12.43-1~bpo12+1

6.12.43-1

6.12.48-1

6.12.57-1~bpo12+1

6.12.57-1

6.12.63-1~bpo12+1

6.12.63-1

6.12.69-1~bpo12+1

6.12.69-1

6.12.73-1~bpo12+1

6.12.73-1

6.12.74-1

6.12.74-2~bpo12+1

6.12.74-2

6.12.85-1~bpo12+1

6.12.85-1

6.12.86-1~bpo12+1

6.12.86-1

6.12.88-1~bpo12+1

6.12.88-1

6.12.90-1~bpo12+1

6.12.90-1

6.12.90-2~bpo12+1

6.12.90-2

6.12.94-1~bpo12+1

6.12.94-1

6.12.95-1~bpo12+1

6.12.95-1

6.12.96-1

6.12.100-1

6.12.101-1

6.12.105-1

6.12.107-1

6.13~rc6-1~exp1

6.13~rc7-1~exp1

6.13.2-1~exp1

6.13.3-1~exp1

6.13.4-1~exp1

6.13.5-1~exp1

6.13.6-1~exp1

6.13.7-1~exp1

6.13.8-1~exp1

6.13.9-1~exp1

6.13.10-1~exp1

6.13.11-1~exp1

6.14.3-1~exp1

6.14.5-1~exp1

6.14.6-1~exp1

6.15~rc7-1~exp1

6.15-1~exp1

6.15.1-1~exp1

6.15.2-1~exp1

6.15.3-1~exp1

6.15.4-1~exp1

6.15.5-1~exp1

6.15.6-1~exp1

6.16~rc7-1~exp1

6.16-1~exp1

6.16.1-1~exp1

6.16.3-1~bpo13+1

6.16.3-1

6.16.5-1

6.16.6-1

6.16.7-1

6.16.8-1

6.16.9-1

6.16.10-1

6.16.11-1

6.16.12-1~bpo13+1

6.16.12-1

6.16.12-2

6.17.2-1~exp1

6.17.5-1~exp1

6.17.6-1

6.17.7-1

6.17.7-2

6.17.8-1~bpo13+1

6.17.8-1

6.17.9-1

6.17.10-1

6.17.11-1

6.17.12-1

6.17.13-1~bpo13+1

6.17.13-1

6.18~rc4-1~exp1

6.18~rc4-1~exp2

6.18~rc5-1~exp1

6.18~rc6-1~exp1

6.18~rc7-1~exp1

6.18.1-1~exp1

6.18.2-1~exp1

6.18.3-1

6.18.5-1~bpo13+1

6.18.5-1

6.18.8-1

6.18.9-1~bpo13+1

6.18.9-1

6.18.10-1

6.18.12-1~bpo13+1

6.18.12-1

6.18.13-1

6.18.14-1

6.18.15-1~bpo13+1

6.18.15-1

6.19~rc4-1~exp1

6.19~rc5-1~exp1

6.19~rc6-1~exp1

6.19~rc7-1~exp1

6.19~rc8-1~exp1

6.19-1~exp1

6.19.2-1~exp1

6.19.3-1~exp1

6.19.4-1~exp1

6.19.5-1~exp1

6.19.6-1

6.19.6-2~bpo13+1

6.19.6-2

6.19.8-1~bpo13+1

6.19.8-1

6.19.10-1~bpo13+1

6.19.10-1

6.19.11-1~bpo13+1

6.19.11-1

6.19.12-1

6.19.13-1~bpo13+1

6.19.13-1

6.19.14-1~bpo13+1

6.19.14-1

7.*

7.0-1~exp1

7.0.1-1~exp1

7.0.3-1

7.0.4-1~bpo13+1

7.0.4-1

7.0.7-1~bpo13+1

7.0.7-1

7.0.9-1~bpo13+1

7.0.9-1

7.0.10-1~bpo13+1

7.0.10-1

7.0.12-1

7.0.12-2~bpo13+1

7.0.12-2

7.0.13-1~bpo13+1

7.0.13-1

7.0.14-1

7.1~rc2-1~exp1

7.1~rc3-1~exp1

7.1~rc4-1~exp1

7.1~rc4-1~exp2

7.1~rc5-1~exp1

7.1~rc7-1~exp1

7.1.1-1~exp1

7.1.2-1~exp1

7.1.3-1~bpo13+1

7.1.3-1

7.1.3-1+sunvdc

7.1.4-1

7.1.5-1

7.1.6-1

7.1.7-1~bpo13+1

7.1.7-1

7.1.8-1~bpo13+1

7.1.8-1

7.1.8-2

7.1.9-1

7.1.9-1+sparc64

7.1.10-1

7.1.12-1

7.1.13-1

7.2~rc3-1~exp1

7.2~rc5-1~exp1

7.2~rc7-1~exp1

7.2.2-1~exp1

7.2.3-1~exp1

Ecosystem specific

{
    "urgency": "not yet assigned"
}

Database specific

source

"https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2026-89768.json"

Debian:14 / linux