tty: synclink_gt: unwind actions in error path of net device open

Resent again, last attempt still altered the plain text.

Zhengchao Shao <shaozhengchao@huawei.com> identified by inspection bugs in the error path of hdlcdev_open() in synclink_gt.c

The function did not fully unwind actions in the error path. The use of try_module_get()/module_put() is unnecessary, potentially hazardous and is removed. The synclink_gt driver is already pinned any point the net device is registered, a requirement for calling this entry point.

The call hdlc_open() to init the generic HDLC layer is moved to after driver level init/checks and proper rollback of previous actions is added. This is a more sensible ordering as the most common error paths are at the driver level and the driver level rollbacks require less processing than hdlc_open()/hdlc_close().

This has been tested with supported hardware.

Signed-off-by:Paul Fulghum <paulkf@microgate.com>

Link: https://lore.kernel.org/r/7599F007-8985-4469-BE00-52BD1530210E@microgate.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/tty/synclink_gt.c b/drivers/tty/synclink_gt.c
index 25e9befdda3a8f07ff4b13bf4e315bc132bc5f79..72b76cdde534d313c5a261079b5b176e02366d79 100644 (file)
--- a/drivers/tty/synclink_gt.c
+++ b/drivers/tty/synclink_gt.c
@@ -1433,16 +1433,8 @@ static int hdlcdev_open(struct net_device *dev)
        int rc;
        unsigned long flags;
 
-       if (!try_module_get(THIS_MODULE))
-               return -EBUSY;
-
        DBGINFO(("%s hdlcdev_open\n", dev->name));
 
-       /* generic HDLC layer open processing */
-       rc = hdlc_open(dev);
-       if (rc)
-               return rc;
-
        /* arbitrate between network and tty opens */
        spin_lock_irqsave(&info->netlock, flags);
        if (info->port.count != 0 || info->netcount != 0) {
@@ -1461,6 +1453,16 @@ static int hdlcdev_open(struct net_device *dev)
                return rc;
        }
 
+       /* generic HDLC layer open processing */
+       rc = hdlc_open(dev);
+       if (rc) {
+               shutdown(info);
+               spin_lock_irqsave(&info->netlock, flags);
+               info->netcount = 0;
+               spin_unlock_irqrestore(&info->netlock, flags);
+               return rc;
+       }
+
        /* assert RTS and DTR, apply hardware settings */
        info->signals |= SerialSignal_RTS | SerialSignal_DTR;
        program_hw(info);
@@ -1506,7 +1508,6 @@ static int hdlcdev_close(struct net_device *dev)
        info->netcount=0;
        spin_unlock_irqrestore(&info->netlock, flags);
 
-       module_put(THIS_MODULE);
        return 0;
 }