Commit 08228941 authored by Kuen-Han Tsai's avatar Kuen-Han Tsai Committed by Greg Kroah-Hartman
Browse files

usb: gadget: f_rndis: Refactor bind path to use __free() 



After an bind/unbind cycle, the rndis->notify_req is left stale. If a
subsequent bind fails, the unified error label attempts to free this
stale request, leading to a NULL pointer dereference when accessing
ep->ops->free_request.

Refactor the error handling in the bind path to use the __free()
automatic cleanup mechanism.

Fixes: 45fe3b8e ("usb ethernet gadget: split RNDIS function")
Cc: stable@kernel.org
Signed-off-by: default avatarKuen-Han Tsai <khtsai@google.com>
Link: https://lore.kernel.org/r/20250916-ready-v1-6-4997bf277548@google.com


Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Link: https://lore.kernel.org/r/20250916-ready-v1-6-4997bf277548@google.com
parent 42988380

drivers/usb/gadget/function/f_rndis.c

+35 −50
Original line number Diff line number Diff line
@@ -19,6 +19,8 @@ 


#include <linux/atomic.h>



#include <linux/usb/gadget.h>



#include "u_ether.h"

#include "u_ether_configfs.h"

#include "u_rndis.h"
@@ -662,6 +664,8 @@ rndis_bind(struct usb_configuration *c, struct usb_function *f) 
	struct usb_ep		*ep;



	struct f_rndis_opts *rndis_opts;

	struct usb_os_desc_table        *os_desc_table __free(kfree) = NULL;

	struct usb_request		*request __free(free_usb_request) = NULL;



	if (!can_support_rndis(c))

		return -EINVAL;
@@ -669,12 +673,9 @@ rndis_bind(struct usb_configuration *c, struct usb_function *f) 
	rndis_opts = container_of(f->fi, struct f_rndis_opts, func_inst);



	if (cdev->use_os_string) {

		f->os_desc_table = kzalloc(sizeof(*f->os_desc_table),

					   GFP_KERNEL);

		if (!f->os_desc_table)

		os_desc_table = kzalloc(sizeof(*os_desc_table), GFP_KERNEL);

		if (!os_desc_table)

			return -ENOMEM;

		f->os_desc_n = 1;

		f->os_desc_table[0].os_desc = &rndis_opts->rndis_os_desc;

	}



	rndis_iad_descriptor.bFunctionClass = rndis_opts->class;
@@ -692,16 +693,14 @@ rndis_bind(struct usb_configuration *c, struct usb_function *f) 
		gether_set_gadget(rndis_opts->net, cdev->gadget);

		status = gether_register_netdev(rndis_opts->net);

		if (status)

			goto fail;

			return status;

		rndis_opts->bound = true;

	}



	us = usb_gstrings_attach(cdev, rndis_strings,

				 ARRAY_SIZE(rndis_string_defs));

	if (IS_ERR(us)) {

		status = PTR_ERR(us);

		goto fail;

	}

	if (IS_ERR(us))

		return PTR_ERR(us);

	rndis_control_intf.iInterface = us[0].id;

	rndis_data_intf.iInterface = us[1].id;

	rndis_iad_descriptor.iFunction = us[2].id;
@@ -709,36 +708,30 @@ rndis_bind(struct usb_configuration *c, struct usb_function *f) 
	/* allocate instance-specific interface IDs */

	status = usb_interface_id(c, f);

	if (status < 0)

		goto fail;

		return status;

	rndis->ctrl_id = status;

	rndis_iad_descriptor.bFirstInterface = status;



	rndis_control_intf.bInterfaceNumber = status;

	rndis_union_desc.bMasterInterface0 = status;



	if (cdev->use_os_string)

		f->os_desc_table[0].if_id =

			rndis_iad_descriptor.bFirstInterface;



	status = usb_interface_id(c, f);

	if (status < 0)

		goto fail;

		return status;

	rndis->data_id = status;



	rndis_data_intf.bInterfaceNumber = status;

	rndis_union_desc.bSlaveInterface0 = status;



	status = -ENODEV;



	/* allocate instance-specific endpoints */

	ep = usb_ep_autoconfig(cdev->gadget, &fs_in_desc);

	if (!ep)

		goto fail;

		return -ENODEV;

	rndis->port.in_ep = ep;



	ep = usb_ep_autoconfig(cdev->gadget, &fs_out_desc);

	if (!ep)

		goto fail;

		return -ENODEV;

	rndis->port.out_ep = ep;



	/* NOTE:  a status/notification endpoint is, strictly speaking,
@@ -747,21 +740,19 @@ rndis_bind(struct usb_configuration *c, struct usb_function *f) 
	 */

	ep = usb_ep_autoconfig(cdev->gadget, &fs_notify_desc);

	if (!ep)

		goto fail;

		return -ENODEV;

	rndis->notify = ep;



	status = -ENOMEM;



	/* allocate notification request and buffer */

	rndis->notify_req = usb_ep_alloc_request(ep, GFP_KERNEL);

	if (!rndis->notify_req)

		goto fail;

	rndis->notify_req->buf = kmalloc(STATUS_BYTECOUNT, GFP_KERNEL);

	if (!rndis->notify_req->buf)

		goto fail;

	rndis->notify_req->length = STATUS_BYTECOUNT;

	rndis->notify_req->context = rndis;

	rndis->notify_req->complete = rndis_response_complete;

	request = usb_ep_alloc_request(ep, GFP_KERNEL);

	if (!request)

		return -ENOMEM;

	request->buf = kmalloc(STATUS_BYTECOUNT, GFP_KERNEL);

	if (!request->buf)

		return -ENOMEM;

	request->length = STATUS_BYTECOUNT;

	request->context = rndis;

	request->complete = rndis_response_complete;



	/* support all relevant hardware speeds... we expect that when

	 * hardware is dual speed, all bulk-capable endpoints work at
@@ -778,7 +769,7 @@ rndis_bind(struct usb_configuration *c, struct usb_function *f) 
	status = usb_assign_descriptors(f, eth_fs_function, eth_hs_function,

			eth_ss_function, eth_ss_function);

	if (status)

		goto fail;

		return status;



	rndis->port.open = rndis_open;

	rndis->port.close = rndis_close;
@@ -789,9 +780,18 @@ rndis_bind(struct usb_configuration *c, struct usb_function *f) 
	if (rndis->manufacturer && rndis->vendorID &&

			rndis_set_param_vendor(rndis->params, rndis->vendorID,

					       rndis->manufacturer)) {

		status = -EINVAL;

		goto fail_free_descs;

		usb_free_all_descriptors(f);

		return -EINVAL;

	}



	if (cdev->use_os_string) {

		os_desc_table[0].os_desc = &rndis_opts->rndis_os_desc;

		os_desc_table[0].if_id = rndis_iad_descriptor.bFirstInterface;

		f->os_desc_table = no_free_ptr(os_desc_table);

		f->os_desc_n = 1;



	}

	rndis->notify_req = no_free_ptr(request);



	/* NOTE:  all that is done without knowing or caring about

	 * the network link ... which is unavailable to this code
@@ -802,21 +802,6 @@ rndis_bind(struct usb_configuration *c, struct usb_function *f) 
			rndis->port.in_ep->name, rndis->port.out_ep->name,

			rndis->notify->name);

	return 0;



fail_free_descs:

	usb_free_all_descriptors(f);

fail:

	kfree(f->os_desc_table);

	f->os_desc_n = 0;



	if (rndis->notify_req) {

		kfree(rndis->notify_req->buf);

		usb_ep_free_request(rndis->notify, rndis->notify_req);

	}



	ERROR(cdev, "%s: can't bind, err %d\n", f->name, status);



	return status;

}



void rndis_borrow_net(struct usb_function_instance *f, struct net_device *net)