Commit 42988380 authored by Kuen-Han Tsai's avatar Kuen-Han Tsai Committed by Greg Kroah-Hartman
Browse files

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



After an bind/unbind cycle, the ecm->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: da741b8c ("usb ethernet gadget: split CDC Ethernet function")
Cc: stable@kernel.org
Signed-off-by: default avatarKuen-Han Tsai <khtsai@google.com>
Link: https://lore.kernel.org/r/20250916-ready-v1-5-4997bf277548@google.com


Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Link: https://lore.kernel.org/r/20250916-ready-v1-5-4997bf277548@google.com
parent 47b2116e

drivers/usb/gadget/function/f_ecm.c

+20 −28
Original line number Diff line number Diff line
@@ -8,6 +8,7 @@ 


/* #define VERBOSE_DEBUG */



#include <linux/cleanup.h>

#include <linux/slab.h>

#include <linux/kernel.h>

#include <linux/module.h>
@@ -15,6 +16,8 @@ 
#include <linux/etherdevice.h>

#include <linux/string_choices.h>



#include <linux/usb/gadget.h>



#include "u_ether.h"

#include "u_ether_configfs.h"

#include "u_ecm.h"
@@ -678,6 +681,7 @@ ecm_bind(struct usb_configuration *c, struct usb_function *f) 
	struct usb_ep		*ep;



	struct f_ecm_opts	*ecm_opts;

	struct usb_request	*request __free(free_usb_request) = NULL;



	if (!can_support_ecm(cdev->gadget))

		return -EINVAL;
@@ -711,7 +715,7 @@ ecm_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;

	ecm->ctrl_id = status;

	ecm_iad_descriptor.bFirstInterface = status;
@@ -720,24 +724,22 @@ ecm_bind(struct usb_configuration *c, struct usb_function *f) 


	status = usb_interface_id(c, f);

	if (status < 0)

		goto fail;

		return status;

	ecm->data_id = status;



	ecm_data_nop_intf.bInterfaceNumber = status;

	ecm_data_intf.bInterfaceNumber = status;

	ecm_union_desc.bSlaveInterface0 = status;



	status = -ENODEV;



	/* allocate instance-specific endpoints */

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

	if (!ep)

		goto fail;

		return -ENODEV;

	ecm->port.in_ep = ep;



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

	if (!ep)

		goto fail;

		return -ENODEV;

	ecm->port.out_ep = ep;



	/* NOTE:  a status/notification endpoint is *OPTIONAL* but we
@@ -746,20 +748,18 @@ ecm_bind(struct usb_configuration *c, struct usb_function *f) 
	 */

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

	if (!ep)

		goto fail;

		return -ENODEV;

	ecm->notify = ep;



	status = -ENOMEM;



	/* allocate notification request and buffer */

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

	if (!ecm->notify_req)

		goto fail;

	ecm->notify_req->buf = kmalloc(ECM_STATUS_BYTECOUNT, GFP_KERNEL);

	if (!ecm->notify_req->buf)

		goto fail;

	ecm->notify_req->context = ecm;

	ecm->notify_req->complete = ecm_notify_complete;

	request = usb_ep_alloc_request(ep, GFP_KERNEL);

	if (!request)

		return -ENOMEM;

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

	if (!request->buf)

		return -ENOMEM;

	request->context = ecm;

	request->complete = ecm_notify_complete;



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

	 * hardware is dual speed, all bulk-capable endpoints work at
@@ -778,7 +778,7 @@ ecm_bind(struct usb_configuration *c, struct usb_function *f) 
	status = usb_assign_descriptors(f, ecm_fs_function, ecm_hs_function,

			ecm_ss_function, ecm_ss_function);

	if (status)

		goto fail;

		return status;



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

	 * the network link ... which is unavailable to this code
@@ -788,20 +788,12 @@ ecm_bind(struct usb_configuration *c, struct usb_function *f) 
	ecm->port.open = ecm_open;

	ecm->port.close = ecm_close;



	ecm->notify_req = no_free_ptr(request);



	DBG(cdev, "CDC Ethernet: IN/%s OUT/%s NOTIFY/%s\n",

			ecm->port.in_ep->name, ecm->port.out_ep->name,

			ecm->notify->name);

	return 0;



fail:

	if (ecm->notify_req) {

		kfree(ecm->notify_req->buf);

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

	}



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



	return status;

}



static inline struct f_ecm_opts *to_f_ecm_opts(struct config_item *item)