| Message ID | cc99f08d-4e2f-120c-fd37-03809c92e819@huawei.com (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | [v2] USB: gadget: Fix use-after-free during usb config switch | expand |
On Sat, Nov 12, 2022 at 04:14:27PM +0800, jiantao zhang wrote: > 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" (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(),The ->disconnect() callback 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 use-after-free 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 > do_page_fault+0xa8/0x46c > do_mem_abort+0x3c/0xac > el1_sync_handler+0x40/0x78 > 0xffffff801138f880 (params->resp_avail is an illegal func 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 > rndis_attr_release+0xc/0x14 > kref_put+0x74/0xb8 > config_item_put+0x14/0x1c > configfs_rmdir+0x314/0x374 Please, read the Submitting Patches document on how to provide backtraces in the commit messages and update yours accordingly. > 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 step1,dev->port_usb will > not be set to null. So, a panic will be caused in step3. > ======================================================================= > Fixes:<0a55187a1ec8c> (USB: gadget core: Issue ->disconnect() > callback from usb_gadget_disconnect()) This is malformed tag. Please, read the Submitting Patches document and fix this accordingly. > Signed-off-by: Jiantao Zhang <water.zhangjiantao@huawei.com> > Signed-off-by: TaoXue <xuetao09@huawei.com> > --- > 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 > >
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
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" (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(),The ->disconnect() callback 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 use-after-free 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 do_page_fault+0xa8/0x46c do_mem_abort+0x3c/0xac el1_sync_handler+0x40/0x78 0xffffff801138f880 (params->resp_avail is an illegal func 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 rndis_attr_release+0xc/0x14 kref_put+0x74/0xb8 config_item_put+0x14/0x1c configfs_rmdir+0x314/0x374 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 step1,dev->port_usb will not be set to null. So, a panic will be caused in step3. ======================================================================= Fixes:<0a55187a1ec8c> (USB: gadget core: Issue ->disconnect() callback from usb_gadget_disconnect()) Signed-off-by: Jiantao Zhang <water.zhangjiantao@huawei.com> Signed-off-by: TaoXue <xuetao09@huawei.com> --- 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(-)