Description
JFFS2, as used on One Laptop Per Child (OLPC) build 542 and possibly other Linux systems, when POSIX ACL support is enabled, does not properly store permissions during (1) inode creation or (2) ACL setting, which might allow local users to access restricted files or directories after a remount of a filesystem, related to "legacy modes" and an inconsistency between dentry permissions and inode permissions.
Fixed in Linux distributions
Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.
Debian
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian 4.0 | fai-kernels | 1.17+etch.13etch3 | DSA-1378-2, DSA-1378-1 |
| Debian 4.0 | linux-2.6 | 2.6.18.dfsg.1-13etch3 | DSA-1378-2, DSA-1378-1 |
| Debian 4.0 | user-mode-linux | 2.6.18-1um-2etch.13etch3 | DSA-1378-2, DSA-1378-1 |
Advisories 2
- DSA-1378-2 fai-kernels linux-2.6 user-mode-linux - several vulnerabilities Debian Security (DSA / DLA) · Mar 9, 2026
- DSA-1378-1 fai-kernels linux-2.6 user-mode-linux - several vulnerabilities Debian Security (DSA / DLA) · Mar 9, 2026
References
- [linux-mtd] 20070822 [JFFS2] Fix ACL vs. mode handling. mailing-list
- 26978 third-party-advisory
- 28706 third-party-advisory
- 25838 vdb-entry
- http://git.infradead.org/?p=mtd-2.6.git%3Ba=commitdiff%3Bh=9ed437c50d89eabae763dd422579f73fdebf288d
- http://dev.laptop.org/ticket/2732
- USN-558-1 vendor-advisory
- USN-574-1 vendor-advisory
- 28170 third-party-advisory
- DSA-1378 vendor-advisory