can: bcm: fix warning in bcm_connect/proc_register

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>
Cc: linux-stable <stable@vger.kernel.org>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

1 files changed, 23 insertions, 9 deletions

diff --git a/net/can/bcm.c b/net/can/bcm.c
index 8e999ffdf28b..8af9d25ff988 100644
--- a/net/can/bcm.c
+++ b/net/can/bcm.c
@@ -1549,24 +1549,31 @@ static int bcm_connect(struct socket *sock, struct sockaddr *uaddr, int len,
         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;
@@ -1577,17 +1584,24 @@ static int bcm_connect(struct socket *sock, struct sockaddr *uaddr, int len,
                 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 socket *sock, struct msghdr *msg, size_t size,