linux-kernel - [PATCH] USB: gadget: Fix CFI failure during usb config switch.

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Message-ID: <b4d5fcb42622441189ad0e6ca5b170c0@huawei.com>
Date:   Mon, 7 Nov 2022 08:56:06 +0000
From:   Jiantao Zhang <water.zhangjiantao@...wei.com>
To:     "Xuetao (kirin)" <xuetao09@...wei.com>,
        "gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>,
        "stern@...land.harvard.edu" <stern@...land.harvard.edu>,
        "jakobkoschel@...il.com" <jakobkoschel@...il.com>,
        "geert+renesas@...der.be" <geert+renesas@...der.be>,
        "colin.i.king@...il.com" <colin.i.king@...il.com>,
        "linux-usb@...r.kernel.org" <linux-usb@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
CC:     Caiyadong <caiyadong@...wei.com>,
        xuhaiyang <xuhaiyang5@...ilicon.com>,
        Suzhuangluan <suzhuangluan@...ilicon.com>
Subject: [PATCH] USB: gadget: Fix CFI failure during usb config switch.

This reverts commit 0a55187a1ec8c

In the process of switching USB config from rndis to other config, if function gadget->ops->pullup() return an error,it will inevitably cause a CFI failure(Linux version 5.10.43).

analysis as follows:
======================================================
(1) write /config/usb_gadget/g1/UDC "none"   (init.usb.configfs.rc:2)

gether_disconnect+0x2c/0x1f8     (dev->port_usb = NULL)
rndis_disable+0x4c/0x74
composite_disconnect+0x74/0xb0
configfs_composite_disconnect+0x60/0x7c
usb_gadget_disconnect+0x70/0x124
usb_gadget_unregister_driver+0xc8/0x1d8
gadget_dev_desc_UDC_store+0xec/0x1e4

in function usb_gadget_disconnect(),gadget->udc->driver->disconnect()
will not be called when gadget->ops->pullup() return an error, therefore, pointer dev->port will not be set to NULL.

(2) rm /config/usb_gadget/g1/configs/b.1/f1    (init.usb.configfs.rc:8)
    (f1 -> ../../../../usb_gadget/g1/functions/rndis.gs4)

rndis_deregister+0x28/0x54
rndis_free+0x44/0x7c
usb_put_function+0x14/0x1c
config_usb_cfg_unlink+0xc4/0xe0
configfs_unlink+0x124/0x1c8
vfs_unlink+0x114/0x1dc

(3) rmdir /config/usb_gadget/g1/functions/rndis.gs4
    (init.usb.configfs.rc:11)

CFI failure (target: [<ffffff814bc20c00>] 0000000068f50078):
CPU: 2 PID: 1 Comm: init VIP: 00 Tainted: G   W  O   5.10.43 #1
Call trace:
 __cfi_slowpath+0x300/0x3bc
 rndis_signal_disconnect+0x1e0/0x204
 rndis_close+0x24/0x2c
 eth_stop+0xd0/0x234           (if dev->port_usb != NULL, call rndis_close)
 __dev_close_many+0x204/0x2d4
 dev_close_many+0x48/0x2c8
 rollback_registered_many+0x184/0xdac
 unregister_netdevice_queue+0xf8/0x24c
 rndis_free_inst+0x78/0xc8
 rndis_attr_release+0x3c/0x84
 config_item_release+0x6c/0x180
 configfs_rmdir+0x7e0/0xca0

Since the rndis memory has been freed in step2, function rndis_close cannot be called here. In function eth_stop(), if pointer dev->port_usb is NULL, function rndis_close() will not be called. So, if
gadget->ops->pullup() return an error in step1, a CFI failure will be
caused here.
======================================================
Through above analysis, i think gadget->udc->driver->disconnect() need to be called even if gadget->udc->driver->disconnect() return an error.

Signed-off-by: Jiantao Zhang <water.zhangjiantao@...wei.com>
Signed-off-by: TaoXue <xuetao09@...wei.com>
---
 drivers/usb/gadget/udc/core.c | 20 +++++++++++---------
 1 file changed, 11 insertions(+), 9 deletions(-)

diff --git a/drivers/usb/gadget/udc/core.c b/drivers/usb/gadget/udc/core.c index c63c0c2cf649..b502b2ac4824 100644
--- a/drivers/usb/gadget/udc/core.c
+++ b/drivers/usb/gadget/udc/core.c
@@ -707,9 +707,6 @@ EXPORT_SYMBOL_GPL(usb_gadget_connect);
  * as a disconnect (when a VBUS session is active).  Not all systems
  * support software pullup controls.
  *
- * Following a successful disconnect, invoke the ->disconnect() callback
- * for the current gadget driver so that UDC drivers don't need to.
- *
  * Returns zero on success, else negative errno.
  */
 int usb_gadget_disconnect(struct usb_gadget *gadget) @@ -734,13 +731,8 @@ int usb_gadget_disconnect(struct usb_gadget *gadget)
 	}
 
 	ret = gadget->ops->pullup(gadget, 0);
-	if (!ret) {
+	if (!ret)
 		gadget->connected = 0;
-		mutex_lock(&udc_lock);
-		if (gadget->udc->driver)
-			gadget->udc->driver->disconnect(gadget);
-		mutex_unlock(&udc_lock);
-	}
 
 out:
 	trace_usb_gadget_disconnect(gadget, ret); @@ -1532,6 +1524,11 @@ static void gadget_unbind_driver(struct device *dev)
 	kobject_uevent(&udc->dev.kobj, KOBJ_CHANGE);
 
 	usb_gadget_disconnect(gadget);
+
+	mutex_lock(&udc_lock);
+	udc->driver->disconnect(udc->gadget);
+	mutex_unlock(&udc_lock);
+
 	usb_gadget_disable_async_callbacks(udc);
 	if (gadget->irq)
 		synchronize_irq(gadget->irq);
@@ -1626,6 +1623,11 @@ static ssize_t soft_connect_store(struct device *dev,
 		usb_gadget_connect(udc->gadget);
 	} else if (sysfs_streq(buf, "disconnect")) {
 		usb_gadget_disconnect(udc->gadget);
+
+		mutex_lock(&udc_lock);
+		udc->driver->disconnect(udc->gadget);
+		mutex_unlock(&udc_lock);
+
 		usb_gadget_udc_stop(udc);
 	} else {
 		dev_err(dev, "unsupported command '%s'\n", buf);
--
2.17.1