[PATCH v2 net 4/4] dccp/tcp: Fixup bhash2 bucket when connect() fails.

Kuniyuki Iwashima
2022-11-16T22:28:05Z

If a socket bound to a wildcard address fails to connect(), we
only reset saddr and keep the port. Then, we have to fix up the
bhash2 bucket; otherwise, the bucket has an inconsistent address
in the list.

Also, listen() for such a socket will fire the WARN_ON() in
inet_csk_get_port(). [0]

Note that when a system runs out of memory, we give up fixing the
bucket and unlink sk from bhash and bhash2 by inet_put_port().

[0]:
WARNING: CPU: 0 PID: 207 at net/ipv4/inet_connection_sock.c:548 inet_csk_get_port (net/ipv4/inet_connection_sock.c:548 (discriminator 1))
Modules linked in:
CPU: 0 PID: 207 Comm: bhash2_prev_rep Not tainted 6.1.0-rc3-00799-gc8421681c845 #63
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.0-1.amzn2022.0.1 04/01/2014
RIP: 0010:inet_csk_get_port (net/ipv4/inet_connection_sock.c:548 (discriminator 1))
Code: 74 a7 eb 93 48 8b 54 24 18 0f b7 cb 4c 89 e6 4c 89 ff e8 48 b2 ff ff 49 8b 87 18 04 00 00 e9 32 ff ff ff 0f 0b e9 34 ff ff ff <0f> 0b e9 42 ff ff ff 41 8b 7f 50 41 8b 4f 54 89 fe 81 f6 00 00 ff
RSP: 0018:ffffc900003d7e50 EFLAGS: 00010202
RAX: ffff8881047fb500 RBX: 0000000000004e20 RCX: 0000000000000000
RDX: 000000000000000a RSI: 00000000fffffe00 RDI: 00000000ffffffff
RBP: ffffffff8324dc00 R08: 0000000000000001 R09: 0000000000000001
R10: 0000000000000001 R11: 0000000000000001 R12: 0000000000000000
R13: 0000000000000001 R14: 0000000000004e20 R15: ffff8881054e1280
FS: 00007f8ac04dc740(0000) GS:ffff88842fc00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000020001540 CR3: 00000001055fa003 CR4: 0000000000770ef0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
PKRU: 55555554
Call Trace:
<TASK>
inet_csk_listen_start (net/ipv4/inet_connection_sock.c:1205)
inet_listen (net/ipv4/af_inet.c:228)
__sys_listen (net/socket.c:1810)
__x64_sys_listen (net/socket.c:1819 net/socket.c:1817 net/socket.c:1817)
do_syscall_64 (arch/x86/entry/common.c:50 arch/x86/entry/common.c:80)
entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:120)
RIP: 0033:0x7f8ac051de5d
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 90 f3 0f 1e fa 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d 93 af 1b 00 f7 d8 64 89 01 48
RSP: 002b:00007ffc1c177248 EFLAGS: 00000206 ORIG_RAX: 0000000000000032
RAX: ffffffffffffffda RBX: 0000000020001550 RCX: 00007f8ac051de5d
RDX: ffffffffffffff80 RSI: 0000000000000000 RDI: 0000000000000004
RBP: 00007ffc1c177270 R08: 0000000000000018 R09: 0000000000000007
R10: 0000000020001540 R11: 0000000000000206 R12: 00007ffc1c177388
R13: 0000000000401169 R14: 0000000000403e18 R15: 00007f8ac0723000
</TASK>

Fixes: 28044fc1d495 ("net: Add a bhash2 table hashed by port and address")
Reported-by: syzbot <syzkaller@googlegroups.com>
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
---
include/net/inet_hashtables.h | 1 +
net/dccp/ipv4.c | 3 +--
net/dccp/ipv6.c | 3 +--
net/dccp/proto.c | 3 +--
net/ipv4/inet_hashtables.c | 38 +++++++++++++++++++++++++++++++----
net/ipv4/tcp.c | 3 +--
net/ipv4/tcp_ipv4.c | 3 +--
net/ipv6/tcp_ipv6.c | 3 +--
8 files changed, 41 insertions(+), 16 deletions(-)

diff --git a/include/net/inet_hashtables.h b/include/net/inet_hashtables.h
index ba06e8b52264..69174093078f 100644
--- a/include/net/inet_hashtables.h
+++ b/include/net/inet_hashtables.h
@@ -282,6 +282,7 @@ inet_bhash2_addr_any_hashbucket(const struct sock *sk, const struct net *net, in
* rcv_saddr field should already have been updated when this is called.
*/
int inet_bhash2_update_saddr(struct sock *sk, void *saddr, int family);
+void inet_bhash2_reset_saddr(struct sock *sk);

void inet_bind_hash(struct sock *sk, struct inet_bind_bucket *tb,
struct inet_bind2_bucket *tb2, unsigned short port);
diff --git a/net/dccp/ipv4.c b/net/dccp/ipv4.c
index 95e376e3b911..b780827f5e0a 100644
--- a/net/dccp/ipv4.c
+++ b/net/dccp/ipv4.c
@@ -143,8 +143,7 @@ int dccp_v4_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len)
* This unhashes the socket and releases the local port, if necessary.
*/
dccp_set_state(sk, DCCP_CLOSED);
- if (!(sk->sk_userlocks & SOCK_BINDADDR_LOCK))
- inet_reset_saddr(sk);
+ inet_bhash2_reset_saddr(sk);
ip_rt_put(rt);
sk->sk_route_caps = 0;
inet->inet_dport = 0;
diff --git a/net/dccp/ipv6.c b/net/dccp/ipv6.c
index 94c101ed57a9..602f3432d80b 100644
--- a/net/dccp/ipv6.c
+++ b/net/dccp/ipv6.c
@@ -970,8 +970,7 @@ static int dccp_v6_connect(struct sock *sk, struct sockaddr *uaddr,

late_failure:
dccp_set_state(sk, DCCP_CLOSED);
- if (!(sk->sk_userlocks & SOCK_BINDADDR_LOCK))
- inet_reset_saddr(sk);
+ inet_bhash2_reset_saddr(sk);
__sk_dst_reset(sk);
failure:
inet->inet_dport = 0;
diff --git a/net/dccp/proto.c b/net/dccp/proto.c
index c548ca3e9b0e..85e35c5e8890 100644
--- a/net/dccp/proto.c
+++ b/net/dccp/proto.c
@@ -279,8 +279,7 @@ int dccp_disconnect(struct sock *sk, int flags)

inet->inet_dport = 0;

- if (!(sk->sk_userlocks & SOCK_BINDADDR_LOCK))
- inet_reset_saddr(sk);
+ inet_bhash2_reset_saddr(sk);

sk->sk_shutdown = 0;
sock_reset_flag(sk, SOCK_DONE);
diff --git a/net/ipv4/inet_hashtables.c b/net/ipv4/inet_hashtables.c
index dcb6bc918966..d24a04815f20 100644
--- a/net/ipv4/inet_hashtables.c
+++ b/net/ipv4/inet_hashtables.c
@@ -871,7 +871,7 @@ static void inet_update_saddr(struct sock *sk, void *saddr, int family)
}
}

-int inet_bhash2_update_saddr(struct sock *sk, void *saddr, int family)
+static int __inet_bhash2_update_saddr(struct sock *sk, void *saddr, int family, bool reset)
{
struct inet_hashinfo *hinfo = tcp_or_dccp_get_hashinfo(sk);
struct inet_bind2_bucket *tb2, *new_tb2;
@@ -882,7 +882,11 @@ int inet_bhash2_update_saddr(struct sock *sk, void *saddr, int family)

if (!inet_csk(sk)->icsk_bind2_hash) {
/* Not bind()ed before. */
- inet_update_saddr(sk, saddr, family);
+ if (reset)
+ inet_reset_saddr(sk);
+ else
+ inet_update_saddr(sk, saddr, family);
+
return 0;
}

@@ -891,8 +895,19 @@ int inet_bhash2_update_saddr(struct sock *sk, void *saddr, int family)
* allocation fails.
*/
new_tb2 = kmem_cache_alloc(hinfo->bind2_bucket_cachep, GFP_ATOMIC);
- if (!new_tb2)
+ if (!new_tb2) {
+ if (reset) {
+ /* The (INADDR_ANY, port) bucket might have already been
+ * freed, then we cannot fixup icsk_bind2_hash, so we give
+ * up and unlink sk from bhash/bhash2 not to fire WARN_ON()
+ * in inet_csk_get_port().
+ */
+ inet_put_port(sk);
+ inet_reset_saddr(sk);
+ }
+
return -ENOMEM;
+ }

/* Unlink first not to show the wrong address for other threads. */
head2 = inet_bhashfn_portaddr(hinfo, sk, net, port);
@@ -902,7 +917,10 @@ int inet_bhash2_update_saddr(struct sock *sk, void *saddr, int family)
inet_bind2_bucket_destroy(hinfo->bind2_bucket_cachep, inet_csk(sk)->icsk_bind2_hash);
spin_unlock_bh(&head2->lock);

- inet_update_saddr(sk, saddr, family);
+ if (reset)
+ inet_reset_saddr(sk);
+ else
+ inet_update_saddr(sk, saddr, family);

/* Update bhash2 bucket. */
head2 = inet_bhashfn_portaddr(hinfo, sk, net, port);
@@ -922,8 +940,20 @@ int inet_bhash2_update_saddr(struct sock *sk, void *saddr, int family)

return 0;
}
+
+int inet_bhash2_update_saddr(struct sock *sk, void *saddr, int family)
+{
+ return __inet_bhash2_update_saddr(sk, saddr, family, false);
+}
EXPORT_SYMBOL_GPL(inet_bhash2_update_saddr);

+void inet_bhash2_reset_saddr(struct sock *sk)
+{
+ if (!(sk->sk_userlocks & SOCK_BINDADDR_LOCK))
+ __inet_bhash2_update_saddr(sk, NULL, 0, true);
+}
+EXPORT_SYMBOL_GPL(inet_bhash2_reset_saddr);
+
/* RFC 6056 3.3.4. Algorithm 4: Double-Hash Port Selection Algorithm
* Note that we use 32bit integers (vs RFC 'short integers')
* because 2^16 is not a multiple of num_ephemeral and this
diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index 54836a6b81d6..4f2205756cfe 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -3114,8 +3114,7 @@ int tcp_disconnect(struct sock *sk, int flags)

inet->inet_dport = 0;

- if (!(sk->sk_userlocks & SOCK_BINDADDR_LOCK))
- inet_reset_saddr(sk);
+ inet_bhash2_reset_saddr(sk);

sk->sk_shutdown = 0;
sock_reset_flag(sk, SOCK_DONE);
diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index 23dd7e9df2d5..da46357f501b 100644
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -331,8 +331,7 @@ int tcp_v4_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len)
* if necessary.
*/
tcp_set_state(sk, TCP_CLOSE);
- if (!(sk->sk_userlocks & SOCK_BINDADDR_LOCK))
- inet_reset_saddr(sk);
+ inet_bhash2_reset_saddr(sk);
ip_rt_put(rt);
sk->sk_route_caps = 0;
inet->inet_dport = 0;
diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c
index 2f3ca3190d26..f0548dbcabd2 100644
--- a/net/ipv6/tcp_ipv6.c
+++ b/net/ipv6/tcp_ipv6.c
@@ -346,8 +346,7 @@ static int tcp_v6_connect(struct sock *sk, struct sockaddr *uaddr,

late_failure:
tcp_set_state(sk, TCP_CLOSE);
- if (!(sk->sk_userlocks & SOCK_BINDADDR_LOCK))
- inet_reset_saddr(sk);
+ inet_bhash2_reset_saddr(sk);
failure:
inet->inet_dport = 0;
sk->sk_route_caps = 0;
--
2.30.2