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udp: must lock the socket in udp_disconnect()

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Baozeng Ding reported KASAN traces showing uses after free in
udp_lib_get_port() and other related UDP functions.

A CONFIG_DEBUG_PAGEALLOC=y kernel would eventually crash.

I could write a reproducer with two threads doing :

static int sock_fd;
static void *thr1(void *arg)
{
	for (;;) {
		connect(sock_fd, (const struct sockaddr *)arg,
			sizeof(struct sockaddr_in));
	}
}

static void *thr2(void *arg)
{
	struct sockaddr_in unspec;

	for (;;) {
		memset(&unspec, 0, sizeof(unspec));
	        connect(sock_fd, (const struct sockaddr *)&unspec,
			sizeof(unspec));
        }
}

Problem is that udp_disconnect() could run without holding socket lock,
and this was causing list corruptions.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: Baozeng Ding <sploving1@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Eric Dumazet 2016-10-20 09:39:40 -07:00 committed by David S. Miller
parent 2399d6143f
commit 286c72deab
8 changed files with 18 additions and 8 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
include/net/udp.h
View File

@ -258,6 +258,7 @@ void udp_flush_pending_frames(struct sock *sk);
void udp4_hwcsum(struct sk_buff *skb, __be32 src, __be32 dst);
int udp_rcv(struct sk_buff *skb);
int udp_ioctl(struct sock *sk, int cmd, unsigned long arg);
int __udp_disconnect(struct sock *sk, int flags);
int udp_disconnect(struct sock *sk, int flags);
unsigned int udp_poll(struct file *file, struct socket *sock, poll_table *wait);
struct sk_buff *skb_udp_tunnel_segment(struct sk_buff *skb,

2
net/ipv4/ping.c
View File

@ -994,7 +994,7 @@ struct proto ping_prot = {
.init = ping_init_sock,
.close = ping_close,
.connect = ip4_datagram_connect,
.disconnect = udp_disconnect,
.disconnect = __udp_disconnect,
.setsockopt = ip_setsockopt,
.getsockopt = ip_getsockopt,
.sendmsg = ping_v4_sendmsg,

2
net/ipv4/raw.c
View File

@ -918,7 +918,7 @@ struct proto raw_prot = {
.close = raw_close,
.destroy = raw_destroy,
.connect = ip4_datagram_connect,
.disconnect = udp_disconnect,
.disconnect = __udp_disconnect,
.ioctl = raw_ioctl,
.init = raw_init,
.setsockopt = raw_setsockopt,

13
net/ipv4/udp.c
View File

@ -1345,7 +1345,7 @@ csum_copy_err:
goto try_again;
}
int udp_disconnect(struct sock *sk, int flags)
int __udp_disconnect(struct sock *sk, int flags)
{
struct inet_sock *inet = inet_sk(sk);
/*
@ -1367,6 +1367,15 @@ int udp_disconnect(struct sock *sk, int flags)
sk_dst_reset(sk);
return 0;
}
EXPORT_SYMBOL(__udp_disconnect);
int udp_disconnect(struct sock *sk, int flags)
{
lock_sock(sk);
__udp_disconnect(sk, flags);
release_sock(sk);
return 0;
}
EXPORT_SYMBOL(udp_disconnect);
void udp_lib_unhash(struct sock *sk)
@ -2193,7 +2202,7 @@ int udp_abort(struct sock *sk, int err)
sk->sk_err = err;
sk->sk_error_report(sk);
udp_disconnect(sk, 0);
__udp_disconnect(sk, 0);
release_sock(sk);

2
net/ipv6/ping.c
View File

@ -180,7 +180,7 @@ struct proto pingv6_prot = {
.init = ping_init_sock,
.close = ping_close,
.connect = ip6_datagram_connect_v6_only,
.disconnect = udp_disconnect,
.disconnect = __udp_disconnect,
.setsockopt = ipv6_setsockopt,
.getsockopt = ipv6_getsockopt,
.sendmsg = ping_v6_sendmsg,

2
net/ipv6/raw.c
View File

@ -1241,7 +1241,7 @@ struct proto rawv6_prot = {
.close = rawv6_close,
.destroy = raw6_destroy,
.connect = ip6_datagram_connect_v6_only,
.disconnect = udp_disconnect,
.disconnect = __udp_disconnect,
.ioctl = rawv6_ioctl,
.init = rawv6_init_sk,
.setsockopt = rawv6_setsockopt,

2
net/l2tp/l2tp_ip.c
View File

@ -338,7 +338,7 @@ static int l2tp_ip_disconnect(struct sock *sk, int flags)
if (sock_flag(sk, SOCK_ZAPPED))
return 0;
return udp_disconnect(sk, flags);
return __udp_disconnect(sk, flags);
}
static int l2tp_ip_getname(struct socket *sock, struct sockaddr *uaddr,

2
net/l2tp/l2tp_ip6.c
View File

@ -410,7 +410,7 @@ static int l2tp_ip6_disconnect(struct sock *sk, int flags)
if (sock_flag(sk, SOCK_ZAPPED))
return 0;
return udp_disconnect(sk, flags);
return __udp_disconnect(sk, flags);
}
static int l2tp_ip6_getname(struct socket *sock, struct sockaddr *uaddr,