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| author | Kuniyuki Iwashima <kuniyu@google.com> | 2026-09-04 03:35:28 +0000 |
|---|---|---|
| committer | Jakub Kicinski <kuba@kernel.org> | 2026-09-07 17:40:26 -0700 |
| commit | 8cc3aef0cb198049805ecc061a2cc7b79b0ae43e (patch) | |
| tree | a600c0a78cc9eef39e60a017573cb6f3c407d771 | |
| parent | 3604abae0f368262e8d30dc3480466cb520046c1 (diff) | |
| download | linux-next-8cc3aef0cb198049805ecc061a2cc7b79b0ae43e.tar.gz linux-next-8cc3aef0cb198049805ecc061a2cc7b79b0ae43e.zip | |
tcp: Do not allow buggy transitions between ehash and lhash2.
The following state transitions have long been a playground for
syzbot, and recently AI joined in, reporting a lot more bugs.
* listen() + shutdown() + connect()
* connect() + connect(AF_UNSPEC) + listen()
All the fix attempts would add more code to the fast path, which
is not worth it.
Instead of playing whack-a-mole with these edge-case bugs,
let's disallow these transitions.
Note that unhashed_state is placed in the 4-byte hole after
icsk_pmtu_cookie.
$ pahole -C inet_connection_sock vmlinux
struct inet_connection_sock {
...
__u32 icsk_pmtu_cookie; /* 1208 4 */
unsigned char unhashed_state; /* 1212 1 */
/* XXX 3 bytes hole, try to pack */
Reported-by: Kyle Zeng <kylebot@openai.com>
Closes: https://lore.kernel.org/netdev/20260731140512.566464-1-david.lee@trailofbits.com/
Reported-by: Michal Luczaj <mhal@rbox.co>
Closes: https://lore.kernel.org/netdev/20260803-sockmap-lookup-tcp-leak-v2-0-306e025bfe66@rbox.co/
Reported-by: Hyunwoo Kim <imv4bel@gmail.com>
Closes: https://lore.kernel.org/netdev/20260824033331.1084971-1-imv4bel@gmail.com/
Signed-off-by: Kuniyuki Iwashima <kuniyu@google.com>
Link: https://patch.msgid.link/20260904033543.2635540-2-kuniyu@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
| -rw-r--r-- | include/net/inet_connection_sock.h | 1 | ||||
| -rw-r--r-- | net/ipv4/inet_connection_sock.c | 1 | ||||
| -rw-r--r-- | net/ipv4/inet_hashtables.c | 11 |
3 files changed, 13 insertions, 0 deletions
diff --git a/include/net/inet_connection_sock.h b/include/net/inet_connection_sock.h index 433c2df23076..903499581db7 100644 --- a/include/net/inet_connection_sock.h +++ b/include/net/inet_connection_sock.h @@ -94,6 +94,7 @@ struct inet_connection_sock { u32 icsk_rto_max; __u32 icsk_delack_max; __u32 icsk_pmtu_cookie; + unsigned char unhashed_state; const struct tcp_congestion_ops *icsk_ca_ops; const struct inet_connection_sock_af_ops *icsk_af_ops; const struct tcp_ulp_ops *icsk_ulp_ops; diff --git a/net/ipv4/inet_connection_sock.c b/net/ipv4/inet_connection_sock.c index 6257459bcee2..560ca861b6d0 100644 --- a/net/ipv4/inet_connection_sock.c +++ b/net/ipv4/inet_connection_sock.c @@ -1253,6 +1253,7 @@ struct sock *inet_csk_clone_lock(const struct sock *sk, memset(&newicsk->icsk_accept_queue, 0, sizeof(newicsk->icsk_accept_queue)); + newicsk->unhashed_state = 0; inet_sk_set_state(newsk, TCP_SYN_RECV); inet_clone_ulp(req, newsk, priority); diff --git a/net/ipv4/inet_hashtables.c b/net/ipv4/inet_hashtables.c index ba0faa9ae2bb..5abcb0debb27 100644 --- a/net/ipv4/inet_hashtables.c +++ b/net/ipv4/inet_hashtables.c @@ -803,6 +803,11 @@ int inet_hash(struct sock *sk) inet_init_ehash_secret(); WARN_ON(!sk_unhashed(sk)); + + if (unlikely(inet_csk(sk)->unhashed_state && + inet_csk(sk)->unhashed_state != TCP_LISTEN)) + return -EINVAL; + ilb2 = inet_lhash2_bucket_sk(hashinfo, sk); spin_lock(&ilb2->lock); @@ -832,6 +837,9 @@ void inet_unhash(struct sock *sk) return; sock_rps_delete_flow(sk); + + inet_csk(sk)->unhashed_state = sk->sk_state; + if (sk->sk_state == TCP_LISTEN) { struct inet_listen_hashbucket *ilb2; @@ -1058,6 +1066,9 @@ int __inet_hash_connect(struct inet_timewait_death_row *death_row, int ret, i, low, high; bool local_ports; + if (unlikely(inet_csk(sk)->unhashed_state == TCP_LISTEN)) + return -EINVAL; + if (port) { local_bh_disable(); ret = check_established(death_row, sk, port, NULL, false, |