net/tcp: Fix socket memory leak in TCP-AO failure handling for IPv6
When tcp_ao_copy_all_matching() fails in tcp_v6_syn_recv_sock() it just
exits the function. This ends up causing a memory-leak:
unreferenced object 0xffff0000281a8200 (size 2496):
comm "softirq", pid 0, jiffies 4295174684
hex dump (first 32 bytes):
7f 00 00 06 7f 00 00 06 00 00 00 00 cb a8 88 13 ................
0a 00 03 61 00 00 00 00 00 00 00 00 00 00 00 00 ...a............
backtrace (crc 5ebdbe15):
kmemleak_alloc+0x44/0xe0
kmem_cache_alloc_noprof+0x248/0x470
sk_prot_alloc+0x48/0x120
sk_clone_lock+0x38/0x3b0
inet_csk_clone_lock+0x34/0x150
tcp_create_openreq_child+0x3c/0x4a8
tcp_v6_syn_recv_sock+0x1c0/0x620
tcp_check_req+0x588/0x790
tcp_v6_rcv+0x5d0/0xc18
ip6_protocol_deliver_rcu+0x2d8/0x4c0
ip6_input_finish+0x74/0x148
ip6_input+0x50/0x118
ip6_sublist_rcv+0x2fc/0x3b0
ipv6_list_rcv+0x114/0x170
__netif_receive_skb_list_core+0x16c/0x200
netif_receive_skb_list_internal+0x1f0/0x2d0
This is because in tcp_v6_syn_recv_sock (and the IPv4 counterpart), when
exiting upon error, inet_csk_prepare_forced_close() and tcp_done() need
to be called. They make sure the newsk will end up being correctly
free'd.
tcp_v4_syn_recv_sock() makes this very clear by having the put_and_exit
label that takes care of things. So, this patch here makes sure
tcp_v4_syn_recv_sock and tcp_v6_syn_recv_sock have similar
error-handling and thus fixes the leak for TCP-AO.
Fixes: 06b22ef29591 ("net/tcp: Wire TCP-AO to request sockets")
Signed-off-by: Christoph Paasch <cpaasch@openai.com>
Reviewed-by: Dmitry Safonov <0x7f454c46@gmail.com>
Link: https://patch.msgid.link/20250830-tcpao_leak-v1-1-e5878c2c3173@openai.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c
index 7577e7e..e885629 100644
--- a/net/ipv6/tcp_ipv6.c
+++ b/net/ipv6/tcp_ipv6.c
@@ -1431,17 +1431,17 @@ static struct sock *tcp_v6_syn_recv_sock(const struct sock *sk, struct sk_buff *
ireq = inet_rsk(req);
if (sk_acceptq_is_full(sk))
- goto out_overflow;
+ goto exit_overflow;
if (!dst) {
dst = inet6_csk_route_req(sk, &fl6, req, IPPROTO_TCP);
if (!dst)
- goto out;
+ goto exit;
}
newsk = tcp_create_openreq_child(sk, req, skb);
if (!newsk)
- goto out_nonewsk;
+ goto exit_nonewsk;
/*
* No need to charge this sock to the relevant IPv6 refcnt debug socks
@@ -1525,25 +1525,19 @@ static struct sock *tcp_v6_syn_recv_sock(const struct sock *sk, struct sk_buff *
const union tcp_md5_addr *addr;
addr = (union tcp_md5_addr *)&newsk->sk_v6_daddr;
- if (tcp_md5_key_copy(newsk, addr, AF_INET6, 128, l3index, key)) {
- inet_csk_prepare_forced_close(newsk);
- tcp_done(newsk);
- goto out;
- }
+ if (tcp_md5_key_copy(newsk, addr, AF_INET6, 128, l3index, key))
+ goto put_and_exit;
}
}
#endif
#ifdef CONFIG_TCP_AO
/* Copy over tcp_ao_info if any */
if (tcp_ao_copy_all_matching(sk, newsk, req, skb, AF_INET6))
- goto out; /* OOM */
+ goto put_and_exit; /* OOM */
#endif
- if (__inet_inherit_port(sk, newsk) < 0) {
- inet_csk_prepare_forced_close(newsk);
- tcp_done(newsk);
- goto out;
- }
+ if (__inet_inherit_port(sk, newsk) < 0)
+ goto put_and_exit;
*own_req = inet_ehash_nolisten(newsk, req_to_sk(req_unhash),
&found_dup_sk);
if (*own_req) {
@@ -1570,13 +1564,17 @@ static struct sock *tcp_v6_syn_recv_sock(const struct sock *sk, struct sk_buff *
return newsk;
-out_overflow:
+exit_overflow:
__NET_INC_STATS(sock_net(sk), LINUX_MIB_LISTENOVERFLOWS);
-out_nonewsk:
+exit_nonewsk:
dst_release(dst);
-out:
+exit:
tcp_listendrop(sk);
return NULL;
+put_and_exit:
+ inet_csk_prepare_forced_close(newsk);
+ tcp_done(newsk);
+ goto exit;
}
INDIRECT_CALLABLE_DECLARE(struct dst_entry *ipv4_dst_check(struct dst_entry *,
