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Message-Id: <7599F007-8985-4469-BE00-52BD1530210E@microgate.com>
Date: Tue, 15 Nov 2022 09:38:32 -0800
From: Paul Fulghum <paulkf@...rogate.com>
To: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc: Zhengchao Shao <shaozhengchao@...wei.com>,
"linux-kernel@...r.kernel.org Mailing List"
<linux-kernel@...r.kernel.org>, Jiri Slaby <jirislaby@...nel.org>,
akpm@...ux-foundation.org, weiyongjun1@...wei.com,
yuehaibing@...wei.com
Subject: [PATCH] tty: synclink_gt: unwind actions in error path of net device
open
Resent again, last attempt still altered the plain text.
Zhengchao Shao <shaozhengchao@...wei.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@...rogate.com>
diff --git a/drivers/tty/synclink_gt.c b/drivers/tty/synclink_gt.c
index 25e9befdda3a..72b76cdde534 100644
--- 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;
}
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