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net/tcp: Fix socket memory leak in TCP-AO failure handling for IPv6

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[ Upstream commit fa390321aba0a54d0f7ae95ee4ecde1358bb9234 ]

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: 06b22ef295 ("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>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Christoph Paasch 2025-08-30 15:55:38 -07:00 committed by Greg Kroah-Hartman
parent 609a8ffff5
commit 46d33c878f
1 changed files with 15 additions and 17 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

32
net/ipv6/tcp_ipv6.c
View File

@ -1417,17 +1417,17 @@ static struct sock *tcp_v6_syn_recv_sock(const struct sock *sk, struct sk_buff *
ireq = inet_rsk(req); ireq = inet_rsk(req);
if (sk_acceptq_is_full(sk)) if (sk_acceptq_is_full(sk))
goto out_overflow; goto exit_overflow;
if (!dst) { if (!dst) {
dst = inet6_csk_route_req(sk, &fl6, req, IPPROTO_TCP); dst = inet6_csk_route_req(sk, &fl6, req, IPPROTO_TCP);
if (!dst) if (!dst)
goto out; goto exit;
} }
newsk = tcp_create_openreq_child(sk, req, skb); newsk = tcp_create_openreq_child(sk, req, skb);
if (!newsk) if (!newsk)
goto out_nonewsk; goto exit_nonewsk;
/* /*
* No need to charge this sock to the relevant IPv6 refcnt debug socks * No need to charge this sock to the relevant IPv6 refcnt debug socks
@ -1517,25 +1517,19 @@ static struct sock *tcp_v6_syn_recv_sock(const struct sock *sk, struct sk_buff *
const union tcp_md5_addr *addr; const union tcp_md5_addr *addr;
addr = (union tcp_md5_addr *)&newsk->sk_v6_daddr; addr = (union tcp_md5_addr *)&newsk->sk_v6_daddr;
if (tcp_md5_key_copy(newsk, addr, AF_INET6, 128, l3index, key)) { if (tcp_md5_key_copy(newsk, addr, AF_INET6, 128, l3index, key))
inet_csk_prepare_forced_close(newsk); goto put_and_exit;
tcp_done(newsk);
goto out;
}
} }
} }
#endif #endif
#ifdef CONFIG_TCP_AO #ifdef CONFIG_TCP_AO
/* Copy over tcp_ao_info if any */ /* Copy over tcp_ao_info if any */
if (tcp_ao_copy_all_matching(sk, newsk, req, skb, AF_INET6)) if (tcp_ao_copy_all_matching(sk, newsk, req, skb, AF_INET6))
goto out; /* OOM */ goto put_and_exit; /* OOM */
#endif #endif
if (__inet_inherit_port(sk, newsk) < 0) { if (__inet_inherit_port(sk, newsk) < 0)
inet_csk_prepare_forced_close(newsk); goto put_and_exit;
tcp_done(newsk);
goto out;
}
*own_req = inet_ehash_nolisten(newsk, req_to_sk(req_unhash), *own_req = inet_ehash_nolisten(newsk, req_to_sk(req_unhash),
&found_dup_sk); &found_dup_sk);
if (*own_req) { if (*own_req) {
@ -1562,13 +1556,17 @@ static struct sock *tcp_v6_syn_recv_sock(const struct sock *sk, struct sk_buff *
return newsk; return newsk;
out_overflow: exit_overflow:
__NET_INC_STATS(sock_net(sk), LINUX_MIB_LISTENOVERFLOWS); __NET_INC_STATS(sock_net(sk), LINUX_MIB_LISTENOVERFLOWS);
out_nonewsk: exit_nonewsk:
dst_release(dst); dst_release(dst);
out: exit:
tcp_listendrop(sk); tcp_listendrop(sk);
return NULL; 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 *, INDIRECT_CALLABLE_DECLARE(struct dst_entry *ipv4_dst_check(struct dst_entry *,