In the process of switching USB config from rndis to other config,
if the hardware does not support the ->pullup callback, or the
hardware encounters a low probability fault, both of them may cause
the ->pullup callback to fail, which will then cause a system panic
(use after free).
The gadget drivers sometimes need to be unloaded regardless of the
hardware's behavior.
Analysis as follows:
=======================================================================
(1) write /config/usb_gadget/g1/UDC "none"
gether_disconnect+0x2c/0x1f8
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
(2) rm /config/usb_gadget/g1/configs/b.1/f1
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
panic+0x1fc/0x3d0
do_page_fault+0xa8/0x46c
do_mem_abort+0x3c/0xac
el1_sync_handler+0x40/0x78
0xffffff801138f880
rndis_close+0x28/0x34
eth_stop+0x74/0x110
dev_close_many+0x48/0x194
rollback_registered_many+0x118/0x814
unregister_netdev+0x20/0x30
gether_cleanup+0x1c/0x38
rndis_attr_release+0xc/0x14
kref_put+0x74/0xb8
configfs_rmdir+0x314/0x374
If gadget->ops->pullup() return an error, function rndis_close() will be
called, then it will causes a use-after-free problem.
=======================================================================
Fixes: 0a55187a1ec8 ("USB: gadget core: Issue ->disconnect() callback from usb_gadget_disconnect()")
Signed-off-by: Jiantao Zhang <water.zhangjiantao@xxxxxxxxxx>
Signed-off-by: TaoXue <xuetao09@xxxxxxxxxx>
---
V3 -> V4: Solved format and mailbox configuration issues.
V2 -> V3: Solved the format issues of Fixes and backtraces.
V1 -> V2: V1 will affect the original function, V2 just move
the callback after "if" statement, so that the original function
will not be affected. And fixed formatting issues.
drivers/usb/gadget/udc/core.c | 12 ++++++------
1 file changed, 6 insertions(+), 6 deletions(-)
diff --git a/drivers/usb/gadget/udc/core.c b/drivers/usb/gadget/udc/core.c
index c63c0c2cf649..bf9878e1a72a 100644
--- a/drivers/usb/gadget/udc/core.c
+++ b/drivers/usb/gadget/udc/core.c
@@ -734,13 +734,13 @@ 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);
- }
+
+ mutex_lock(&udc_lock);
+ if (gadget->udc->driver)
+ gadget->udc->driver->disconnect(gadget);
+ mutex_unlock(&udc_lock);
out:
trace_usb_gadget_disconnect(gadget, ret);
--
2.17.1
