nfsd: release path refs on follow_down() error
- Published
- Last modified
- Where the record stands: published, rejected by its publisher, or superseded by another id.What do these mean? →
- published
- Whether CISA lists it in its Known Exploited Vulnerabilities catalog: proof that attackers are using it.What do these mean? →
- Not listed in CISA KEV
- Fix
- Fixed in 6.6.157, 6.12.109, 6.18.50, 7.2.4
- Whether working attack code is public (Exploit-DB, Metasploit, Nuclei or GitHub). Public code makes attacks easier.What do these mean? →
- None on Exploit-DB, Metasploit or GitHub
- Exploitation: none
- Automatable: yes
- Technical impact: partial
Summary
In the Linux kernel, the following vulnerability has been resolved: nfsd: release path refs on follow_down() error nfsd_cross_mnt() initializes a local struct path with mntget() and dget() before calling follow_down(). On a negative return the error arm jumps to out without releasing those references: err = follow_down(&path, follow_flags); if (err < 0) goto out; follow_down() never drops the caller's entry-time refs on any error sub-case; for example a pre-cross d_manage() failure leaves path untouched, so the mntget()/dget() taken on entry survive the call. Every other early-exit arm in nfsd_cross_mnt() (other-namespace return, IS_ERR(exp2), and the success tail after the swap) already calls path_put(&path); the err < 0 arm is the lone omission. The leak inflates mnt_count and d_count on each failed cross-mount, blocking umount and pinning dentries against the shrinker, and is reachable by any authenticated NFS client through nfsd_lookup_dentry or the NFSv4 READDIR encode path. Fix by calling path_put(&path) before the goto out in the err < 0 arm so the entry-time refs are released on all follow_down() error returns.
Timeline
- CVE published
- CISA SSVC assessment
Exploitation: none · Automatable: yes · Technical impact: partial
- Record last updated
Affected versions
- Linux Linux
From cc53ce53c86924bfe98a12ea20b7465038a08792 · fixed in 085cfde7c2186acaad103f02d2c25435ad5224e9; From cc53ce53c86924bfe98a12ea20b7465038a08792 · fixed in 194316df81263519156ebe714c4a286bee00e5be; From cc53ce53c86924bfe98a12ea20b7465038a08792 · fixed in 467d56fd3ff57447a790c6dc3ede2d02a947d224; From cc53ce53c86924bfe98a12ea20b7465038a08792 · fixed in 2bc4343308d85ee4e0dd3877b384306c96f114c2; From cc53ce53c86924bfe98a12ea20b7465038a08792 · fixed in 6cba08dc1922140d260cfeb30bbda4ee1bf869d8
- Linux Linux
2.6.38
- KernelLinux
From 2.6.38 · fixed in 6.6.157; From 6.7.0 · fixed in 6.12.109; From 6.13.0 · fixed in 6.18.50; From 6.19.0 · fixed in 7.2.4