net/tcp-ao: fix use-after-free of current_key on reconnect to another peer
- 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- Where the record stands: published, rejected by its publisher, or superseded by another id.What do these mean?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 6.12.108, 6.18.49, 7.1.13, 7.2.3
- 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
Summary
In the Linux kernel, the following vulnerability has been resolved: net/tcp-ao: fix use-after-free of current_key on reconnect to another peer tcp_inbound_ao_hash() is called before bh_lock_sock_nested() is taken, with only rcu_read_lock() held. On the fast path for established sockets, if the rnext_keyid sent by the peer differs from current_key->sndid, the key the peer asked for is looked up and stored in current_key. The lookup is inside the RCU read side, but current_key outlives it. When the socket is disconnected and connect() is called again for another peer, tcp_ao_connect_init() unlinks every key that does not match the new peer and frees it with call_rcu(). If current_key points at such a key, it is cleared to NULL. The fast path reads sk_state only once on entry, so a softirq that got into it while the socket was still established can update current_key after that loop has already run. The update is inside the RCU read side, so it comes before the call_rcu() callback, and once the callback frees the key, current_key is left pointing at freed memory. The next transmission picks that pointer up in tcp_get_current_key(). tcp_ao_transmit_skb() then reads the traffic key from the freed object, which is the use-after-free. Wait for one grace period before unlinking, and only if a key is going to be removed. By the time tcp_connect() runs the socket is already in TCP_SYN_SENT, and TCP_AO_ESTABLISHED does not contain TCPF_SYN_SENT, so a softirq entering after the wait cannot reach the fast path, and the ones already in it have finished. The existing NULL handling in the loop is then enough.
Timeline
- CVE published
- Record last updated
Affected versions
- Linux Linux
From 0a3a809089eb1d4a0a2fd0c16b520d603988c859 · fixed in 84a93b4e012587d0a4a84ffb23ec6da18e9d85f9; From 0a3a809089eb1d4a0a2fd0c16b520d603988c859 · fixed in 73fde8fe4469f4ed8f0afcc0b9d6413002a9e6b3; From 0a3a809089eb1d4a0a2fd0c16b520d603988c859 · fixed in e54ad693eddb40c595add013f545354c538e325b; From 0a3a809089eb1d4a0a2fd0c16b520d603988c859 · fixed in 2857dcbd03cf3354af0fba1b65c6a260fb43811a; From 0a3a809089eb1d4a0a2fd0c16b520d603988c859 · fixed in da4471557f279d0f56605158a625bb6e49ef7d41
- Linux Linux
6.7
- KernelLinux
From 6.7.0 · fixed in 6.12.108; From 6.13.0 · fixed in 6.18.49; From 6.19.0 · fixed in 7.1.13; From 7.2.0 · fixed in 7.2.3