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 system panic(use after free).
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 general, pointer dev->port will be set to null.
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.
If pointer dev->port_usb is not null, it will cause an exception of using
the freed memory in step3.
(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 (kfree(params))
rndis_free+0x44/0x7c (kfree(rndis))
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)
Call trace:
panic+0x1fc/0x3d0
die+0x29c/0x2a8
die_kernel_fault+0x60/0x90
do_page_fault+0xa8/0x46c
do_mem_abort+0x3c/0xac
el1_abort+0x3c/0x58
el1_sync_handler+0x40/0x78
el1_sync+0x84/0x140
0xffffff801138f880 (params->resp_avail is an illegal function pointer)
rndis_close+0x28/0x34 (->rndis_indicate_status_msg-> params->resp_avail())
eth_stop+0x74/0x110 (if dev->port_usb != NULL, call rndis_close)
__dev_close_many+0x134/0x194
dev_close_many+0x48/0x194
rollback_registered_many+0x118/0x814
unregister_netdevice_queue+0xe0/0x168
unregister_netdev+0x20/0x30
gether_cleanup+0x1c/0x38
rndis_free_inst+0x2c/0x58
usb_put_function_instance+0x20/0x34
rndis_attr_release+0xc/0x14
kref_put+0x74/0xb8
config_item_put+0x14/0x1c
configfs_rmdir+0x314/0x374
vfs_rmdir+0xa4/0x15c
In step3,function pointer params->resp_avail() is a wild pointer
becase pointer params has been freed in step2.
Free mem stack(in step2):
usb_put_function -> rndis_free -> rndis_deregister -> kfree(params)
use-after-free stack(in step3):
eth_stop -> rndis_close -> rndis_signal_disconnect ->
rndis_indicate_status_msg -> params->resp_avail()
In function eth_stop(), if pointer dev->port_usb is NULL, function
rndis_close() will not be called.
If gadget->ops->pullup() return an error in step),dev->port_usb will
not be set to null. So, a panic will be caused in step3.
=======================================================================
Through above analysis, i think gadget->udc->driver->disconnect() need
to be called even if gadget->udc->driver->disconnect() return an error.
This reverts commit 0a55187a1ec8c03d0619e7ce41d10fdc39cff036
I think this change is a code optimization, not a solution to specific
problem. And i think this problem is caused by this change,revert it can
solve this problem.
Of course, my understanding may be inaccurate.There may be a better
solution to this problem. If possible, please give some suggestions,
thanks.
Fixes:<0a55187a1ec8c> (USB: gadget core: Issue ->disconnect()
callback from usb_gadget_disconnect())
Signed-off-by: Jiantao Zhang <water.zhangjiantao@xxxxxxxxxx>
Signed-off-by: TaoXue <xuetao09@xxxxxxxxxx>
---
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);
