l2tp: pppol2tp: hold reference to session in pppol2tp_ioctl()
- 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- Where the record stands: published, rejected by its publisher, or superseded by another id.What do these mean?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 6.6.160, 6.12.94, 6.18.36, 7.0.13
- 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: no
- Technical impact: total
Summary
In the Linux kernel, the following vulnerability has been resolved: l2tp: pppol2tp: hold reference to session in pppol2tp_ioctl() pppol2tp_ioctl() read sock->sk->sk_user_data directly without any locks or reference counting. If a controllable sleep was induced during copy_from_user() (e.g. via a userfaultfd page fault sleep), a concurrent socket close could trigger pppol2tp_session_close() asynchronously. This frees the l2tp_session structure via the l2tp_session_del_work workqueue. Upon resuming, the ioctl thread dereferences the stale session pointer, resulting in a Use-After-Free (UAF). Fix this by securely fetching the session reference using the RCU-safe, refcounted helper pppol2tp_sock_to_session(sk) on entry. This locks the session's refcount across the sleep. We structured the function to exit via standard err breaks, guaranteeing that l2tp_session_put() is cleanly called on all return paths to drop the reference. To preserve existing behavior we validate the session and its magic signature only for the specific L2TP commands that require it. This ensures that generic/unknown ioctls called on an unconnected socket still return -ENOIOCTLCMD and correctly fall back to generic handlers (e.g. in sock_do_ioctl()).
Timeline
- CVE published
- CISA SSVC assessment
Exploitation: none · Automatable: no · Technical impact: total
- Record last updated
Affected versions
- Linux Linux
From fd558d186df2c13a22455373858bae634a4795af · fixed in 312ecea13b67797747eb9d4b9dab8d3846de6dfb; From fd558d186df2c13a22455373858bae634a4795af · fixed in 78cdfdca88cbf731a92f3b9ee5427c633dd94e28; From fd558d186df2c13a22455373858bae634a4795af · fixed in e251d4cdfc725c9e7d686161e3b775a0e7d95053; From fd558d186df2c13a22455373858bae634a4795af · fixed in 62f327e287cf7b595ae3f73ba72f5cd2a9e9f39f; From fd558d186df2c13a22455373858bae634a4795af · fixed in a213a8950414c684999dcf03edeea6c46ede172e
- Linux Linux
2.6.35
- KernelLinux
From 2.6.35 · fixed in 6.6.160; From 6.7.0 · fixed in 6.12.94; From 6.13.0 · fixed in 6.18.36; From 6.19.0 · fixed in 7.0.13