CVE-2024-26821

NameCVE-2024-26821
DescriptionIn the Linux kernel, the following vulnerability has been resolved: fs: relax mount_setattr() permission checks When we added mount_setattr() I added additional checks compared to the legacy do_reconfigure_mnt() and do_change_type() helpers used by regular mount(2). If that mount had a parent then verify that the caller and the mount namespace the mount is attached to match and if not make sure that it's an anonymous mount. The real rootfs falls into neither category. It is neither an anoymous mount because it is obviously attached to the initial mount namespace but it also obviously doesn't have a parent mount. So that means legacy mount(2) allows changing mount properties on the real rootfs but mount_setattr(2) blocks this. I never thought much about this but of course someone on this planet of earth changes properties on the real rootfs as can be seen in [1]. Since util-linux finally switched to the new mount api in 2.39 not so long ago it also relies on mount_setattr() and that surfaced this issue when Fedora 39 finally switched to it. Fix this.
SourceCVE (at NVD; CERT, LWN, oss-sec, fulldisc, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, GitHub advisories/code/issues, web search, more)

Vulnerable and fixed packages

The table below lists information on source packages.

Source PackageReleaseVersionStatus
linux (PTS)jessie, jessie (lts)3.16.84-1vulnerable
stretch (security)4.9.320-2vulnerable
stretch (lts), stretch4.9.320-3vulnerable
buster4.19.249-2vulnerable
buster (security)4.19.304-1vulnerable
bullseye5.10.209-2vulnerable
bullseye (security)5.10.205-2vulnerable
bookworm6.1.76-1vulnerable
bookworm (security)6.1.85-1fixed
trixie6.6.15-2vulnerable
sid6.7.12-1fixed

The information below is based on the following data on fixed versions.

PackageTypeReleaseFixed VersionUrgencyOriginDebian Bugs
linuxsourcejessie(unfixed)end-of-life
linuxsourcestretch(unfixed)end-of-life
linuxsourcebookworm6.1.82-1
linuxsource(unstable)6.7.7-1

Notes

https://git.kernel.org/linus/46f5ab762d048dad224436978315cbc2fa79c630 (6.8-rc5)

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