sunrpc: wait for in-flight TLS handshake callback when cancel loses race
- 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- Where the record stands: published, rejected by its publisher, or superseded by another id.What do these mean?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 6.6.145, 6.12.97, 6.18.40, 7.1.5
- 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: total
Summary
In the Linux kernel, the following vulnerability has been resolved: sunrpc: wait for in-flight TLS handshake callback when cancel loses race When wait_for_completion_interruptible_timeout() in svc_tcp_handshake() returns 0 (timeout) or -ERESTARTSYS (signal) and tls_handshake_cancel() then returns false, handshake_complete() has won the cancellation race: it has set HANDSHAKE_F_REQ_COMPLETED and is about to invoke svc_tcp_handshake_done(), but the callback's side effects on xpt_flags and on svsk->sk_handshake_done have not yet committed. The current code reads xpt_flags immediately to decide whether the session succeeded. Two races result. If the callback has executed set_bit(XPT_TLS_SESSION) but not yet clear_bit(XPT_HANDSHAKE), svc_tcp_handshake() sees a session, enqueues the transport, and returns. svc_xprt_received() then clears XPT_BUSY, a worker thread picks the transport up, the dispatcher in svc_handle_xprt() observes XPT_HANDSHAKE still set, and xpo_handshake is invoked a second time. That svc_tcp_handshake() calls init_completion(&svsk->sk_handshake_done) while the original callback concurrently calls complete_all() on it, corrupting the embedded swait_queue. If the callback has set HANDSHAKE_F_REQ_COMPLETED but not yet entered svc_tcp_handshake_done(), svc_tcp_handshake() reads XPT_TLS_SESSION as clear and tears the connection down even though the handshake is about to succeed. Wait for the callback to commit before inspecting xpt_flags. The completion is guaranteed to fire because handshake_complete() invokes svc_tcp_handshake_done() unconditionally once it has set HANDSHAKE_F_REQ_COMPLETED.
Timeline
- CVE published
- CISA SSVC assessment
Exploitation: none · Automatable: yes · Technical impact: total
- Record last updated
Affected versions
- Linux Linux
From b3cbf98e2fdf3cb147a95161560cd25987284330 · fixed in 0d8ceb39884148dc7a2fdf71e1cac5961ed1d2b9; From b3cbf98e2fdf3cb147a95161560cd25987284330 · fixed in e0f4691d42a54d359d8b64509fd9ab938d4f2a33; From b3cbf98e2fdf3cb147a95161560cd25987284330 · fixed in 65b23bec1fca6e9ebdc3e6041ebf8c6ab074141b; From b3cbf98e2fdf3cb147a95161560cd25987284330 · fixed in a4f878e8ecd729ccf2e50993444e217583adeace; From b3cbf98e2fdf3cb147a95161560cd25987284330 · fixed in d00e32f84ca1a77cb67a3fbf59f58dada95f5a21
- Linux Linux
6.4
- KernelLinux
From 6.4.0 · fixed in 6.6.145; From 6.7.0 · fixed in 6.12.97; From 6.13.0 · fixed in 6.18.40; From 6.19.0 · fixed in 7.1.5