[PATCH 3.2 068/126] can: bcm: fix warning in bcm_connect/proc_register

Ben Hutchings
2017-02-15T23:04:09Z

From: Oliver Hartkopp <socketcan@hartkopp.net>

commit deb507f91f1adbf64317ad24ac46c56eeccfb754 upstream.

Andrey Konovalov reported an issue with proc_register in bcm.c.
As suggested by Cong Wang this patch adds a lock_sock() protection and
a check for unsuccessful proc_create_data() in bcm_connect().

Reference: http://marc.info/?l=linux-netdev&m=147732648731237

Reported-by: Andrey Konovalov <andreyknvl@google.com>
Suggested-by: Cong Wang <xiyou.wangcong@gmail.com>
Signed-off-by: Oliver Hartkopp <socketcan@hartkopp.net>
Acked-by: Cong Wang <xiyou.wangcong@gmail.com>
Tested-by: Andrey Konovalov <andreyknvl@google.com>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
net/can/bcm.c | 32 +++++++++++++++++++++++---------
1 file changed, 23 insertions(+), 9 deletions(-)

--- a/net/can/bcm.c
+++ b/net/can/bcm.c
@@ -1494,24 +1494,31 @@ static int bcm_connect(struct socket *so
struct sockaddr_can *addr = (struct sockaddr_can *)uaddr;
struct sock *sk = sock->sk;
struct bcm_sock *bo = bcm_sk(sk);
+ int ret = 0;

if (len < sizeof(*addr))
return -EINVAL;

- if (bo->bound)
- return -EISCONN;
+ lock_sock(sk);
+
+ if (bo->bound) {
+ ret = -EISCONN;
+ goto fail;
+ }

/* bind a device to this socket */
if (addr->can_ifindex) {
struct net_device *dev;

dev = dev_get_by_index(&init_net, addr->can_ifindex);
- if (!dev)
- return -ENODEV;
-
+ if (!dev) {
+ ret = -ENODEV;
+ goto fail;
+ }
if (dev->type != ARPHRD_CAN) {
dev_put(dev);
- return -ENODEV;
+ ret = -ENODEV;
+ goto fail;
}

bo->ifindex = dev->ifindex;
@@ -1522,17 +1529,24 @@ static int bcm_connect(struct socket *so
bo->ifindex = 0;
}

- bo->bound = 1;
-
if (proc_dir) {
/* unique socket address as filename */
sprintf(bo->procname, "%lu", sock_i_ino(sk));
bo->bcm_proc_read = proc_create_data(bo->procname, 0644,
proc_dir,
&bcm_proc_fops, sk);
+ if (!bo->bcm_proc_read) {
+ ret = -ENOMEM;
+ goto fail;
+ }
}

- return 0;
+ bo->bound = 1;
+
+fail:
+ release_sock(sk);
+
+ return ret;
}

static int bcm_recvmsg(struct kiocb *iocb, struct socket *sock,