[PATCH 0/6] usb: gadget: Refactor function drivers to use __free() cleanup

[PATCH 0/6] usb: gadget: Refactor function drivers to use __free() cleanup

[Kuen-Han Tsai]

Hello,

This patch series refactors the error-handling paths in the bind()
function for f_ncm, f_acm, f_ecm, and f_rndis drivers. 

The current, unified goto logic in these drivers is vulnerable to a null
pointer dereference. This is caused by the cleanup logic incorrectly
handling the stale usb_request pointer after a bind/unbind cycle. This
series fixes this issue by converting the drivers to use the modern
__free() scope-based cleanup mechanism.

Patches 1-2 are preparatory, adding the endpoint pointer to struct
usb_request and defining helpers for the __free() cleanup. The remaining
four patches use this new plumbing to refactor each driver.

Future work
-----------

1. Refactor usb_ep_free_request(), usb_ep_queue(), and usb_ep_dequeue()
   functions as the ep parameter becomes redudant.
2. Convert the remaining gadget function drivers to use the new __free()
   cleanup mechanism.

Signed-off-by: Kuen-Han Tsai <khtsai@google.com>
---
Kuen-Han Tsai (6):
      usb: gadget: Store endpoint pointer in usb_request
      usb: gadget: Introduce free_usb_request helper
      usb: gadget: f_ncm: Refactor bind path to use __free()
      usb: gadget: f_acm: Refactor bind path to use __free()
      usb: gadget: f_ecm: Refactor bind path to use __free()
      usb: gadget: f_rndis: Refactor bind path to use __free()

 drivers/usb/gadget/function/f_acm.c   | 42 ++++++++---------
 drivers/usb/gadget/function/f_ecm.c   | 48 +++++++++-----------
 drivers/usb/gadget/function/f_ncm.c   | 78 ++++++++++++++------------------
 drivers/usb/gadget/function/f_rndis.c | 85 +++++++++++++++--------------------
 drivers/usb/gadget/udc/core.c         |  3 ++
 include/linux/usb/gadget.h            | 25 +++++++++++
 6 files changed, 135 insertions(+), 146 deletions(-)
---
base-commit: 1b237f190eb3d36f52dffe07a40b5eb210280e00
change-id: 20250916-ready-70b1c55d14b6

Best regards,
-- 
Kuen-Han Tsai <khtsai@google.com>

[PATCH 1/6] usb: gadget: Store endpoint pointer in usb_request

[Kuen-Han Tsai]

Gadget function drivers often have goto-based error handling in their
bind paths, which can be bug-prone. Refactoring these paths to use
__free() scope-based cleanup is desirable, but currently blocked.

The blocker is that usb_ep_free_request(ep, req) requires two
parameters, while the __free() mechanism can only pass a pointer to the
request itself.

Store an endpoint pointer in the struct usb_request. The pointer is
populated centrally in usb_ep_alloc_request() on every successful
allocation, making the request object self-contained.

Signed-off-by: Kuen-Han Tsai <khtsai@google.com>
---
 drivers/usb/gadget/udc/core.c | 3 +++
 include/linux/usb/gadget.h    | 2 ++
 2 files changed, 5 insertions(+)

diff --git a/drivers/usb/gadget/udc/core.c b/drivers/usb/gadget/udc/core.c
index d709e24c1fd4228c47f877d097faf987975ac392..e3d63b8fa0f4c17c6d59ab9d2f2c529e98f20d45 100644
--- a/drivers/usb/gadget/udc/core.c
+++ b/drivers/usb/gadget/udc/core.c
@@ -194,6 +194,9 @@ struct usb_request *usb_ep_alloc_request(struct usb_ep *ep,
 
 	req = ep->ops->alloc_request(ep, gfp_flags);
 
+	if (req)
+		req->ep = ep;
+
 	trace_usb_ep_alloc_request(ep, req, req ? 0 : -ENOMEM);
 
 	return req;
diff --git a/include/linux/usb/gadget.h b/include/linux/usb/gadget.h
index 0f28c5512fcb6ccd7a854ae8a66c21aec194c3c7..0f20794760887314d81a070755c8908c6ac4ed90 100644
--- a/include/linux/usb/gadget.h
+++ b/include/linux/usb/gadget.h
@@ -32,6 +32,7 @@ struct usb_ep;
 
 /**
  * struct usb_request - describes one i/o request
+ * @ep: The associated endpoint set by usb_ep_alloc_request().
  * @buf: Buffer used for data.  Always provide this; some controllers
  *	only use PIO, or don't use DMA for some endpoints.
  * @dma: DMA address corresponding to 'buf'.  If you don't set this
@@ -98,6 +99,7 @@ struct usb_ep;
  */
 
 struct usb_request {
+	struct usb_ep		*ep;
 	void			*buf;
 	unsigned		length;
 	dma_addr_t		dma;

-- 
2.51.0.384.g4c02a37b29-goog

[PATCH 2/6] usb: gadget: Introduce free_usb_request helper

[Kuen-Han Tsai]

Introduce the free_usb_request() function that frees both the request's
buffer and the request itself.

This function serves as the cleanup callback for DEFINE_FREE() to enable
automatic, scope-based cleanup for usb_request pointers.

Signed-off-by: Kuen-Han Tsai <khtsai@google.com>
---
 include/linux/usb/gadget.h | 23 +++++++++++++++++++++++
 1 file changed, 23 insertions(+)

diff --git a/include/linux/usb/gadget.h b/include/linux/usb/gadget.h
index 0f20794760887314d81a070755c8908c6ac4ed90..3aaf19e775580b19cbb2b30d8df8a282945edfa0 100644
--- a/include/linux/usb/gadget.h
+++ b/include/linux/usb/gadget.h
@@ -15,6 +15,7 @@
 #ifndef __LINUX_USB_GADGET_H
 #define __LINUX_USB_GADGET_H
 
+#include <linux/cleanup.h>
 #include <linux/configfs.h>
 #include <linux/device.h>
 #include <linux/errno.h>
@@ -293,6 +294,28 @@ static inline void usb_ep_fifo_flush(struct usb_ep *ep)
 
 /*-------------------------------------------------------------------------*/
 
+/**
+ * free_usb_request - frees a usb_request object and its buffer
+ * @req: the request being freed
+ *
+ * This helper function frees both the request's buffer and the request object
+ * itself by calling usb_ep_free_request(). Its signature is designed to be used
+ * with DEFINE_FREE() to enable automatic, scope-based cleanup for usb_request
+ * pointers.
+ */
+static inline void free_usb_request(struct usb_request *req)
+{
+	if (!req)
+		return;
+
+	kfree(req->buf);
+	usb_ep_free_request(req->ep, req);
+}
+
+DEFINE_FREE(free_usb_request, struct usb_request *, free_usb_request(_T))
+
+/*-------------------------------------------------------------------------*/
+
 struct usb_dcd_config_params {
 	__u8  bU1devExitLat;	/* U1 Device exit Latency */
 #define USB_DEFAULT_U1_DEV_EXIT_LAT	0x01	/* Less then 1 microsec */

-- 
2.51.0.384.g4c02a37b29-goog

[PATCH 3/6] usb: gadget: f_ncm: Refactor bind path to use __free()

[Kuen-Han Tsai]

After an bind/unbind cycle, the ncm->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.

Unable to handle kernel NULL pointer dereference at virtual address 0000000000000020
Call trace:
 usb_ep_free_request+0x2c/0xec
 ncm_bind+0x39c/0x3dc
 usb_add_function+0xcc/0x1f0
 configfs_composite_bind+0x468/0x588
 gadget_bind_driver+0x104/0x270
 really_probe+0x190/0x374
 __driver_probe_device+0xa0/0x12c
 driver_probe_device+0x3c/0x218
 __device_attach_driver+0x14c/0x188
 bus_for_each_drv+0x10c/0x168
 __device_attach+0xfc/0x198
 device_initial_probe+0x14/0x24
 bus_probe_device+0x94/0x11c
 device_add+0x268/0x48c
 usb_add_gadget+0x198/0x28c
 dwc3_gadget_init+0x700/0x858
 __dwc3_set_mode+0x3cc/0x664
 process_scheduled_works+0x1d8/0x488
 worker_thread+0x244/0x334
 kthread+0x114/0x1bc
 ret_from_fork+0x10/0x20

Fixes: 9f6ce4240a2b ("usb: gadget: f_ncm.c added")
Cc: stable@kernel.org
Signed-off-by: Kuen-Han Tsai <khtsai@google.com>
---
 drivers/usb/gadget/function/f_ncm.c | 78 ++++++++++++++++---------------------
 1 file changed, 33 insertions(+), 45 deletions(-)

diff --git a/drivers/usb/gadget/function/f_ncm.c b/drivers/usb/gadget/function/f_ncm.c
index 58b0dd575af32a95f8ae1fa7d9483638d37fd052..0148d60926dcf751b7c464c2922d194ef965bdfd 100644
--- a/drivers/usb/gadget/function/f_ncm.c
+++ b/drivers/usb/gadget/function/f_ncm.c
@@ -11,6 +11,7 @@
  * Copyright (C) 2008 Nokia Corporation
  */
 
+#include <linux/cleanup.h>
 #include <linux/kernel.h>
 #include <linux/interrupt.h>
 #include <linux/module.h>
@@ -20,6 +21,7 @@
 #include <linux/string_choices.h>
 
 #include <linux/usb/cdc.h>
+#include <linux/usb/gadget.h>
 
 #include "u_ether.h"
 #include "u_ether_configfs.h"
@@ -1436,18 +1438,18 @@ static int ncm_bind(struct usb_configuration *c, struct usb_function *f)
 	struct usb_ep		*ep;
 	struct f_ncm_opts	*ncm_opts;
 
+	struct usb_os_desc_table	*os_desc_table __free(kfree) = NULL;
+	struct usb_request		*request __free(free_usb_request) = NULL;
+
 	if (!can_support_ecm(cdev->gadget))
 		return -EINVAL;
 
 	ncm_opts = container_of(f->fi, struct f_ncm_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 = &ncm_opts->ncm_os_desc;
 	}
 
 	mutex_lock(&ncm_opts->lock);
@@ -1459,16 +1461,15 @@ static int ncm_bind(struct usb_configuration *c, struct usb_function *f)
 	mutex_unlock(&ncm_opts->lock);
 
 	if (status)
-		goto fail;
+		return status;
 
 	ncm_opts->bound = true;
 
 	us = usb_gstrings_attach(cdev, ncm_strings,
 				 ARRAY_SIZE(ncm_string_defs));
-	if (IS_ERR(us)) {
-		status = PTR_ERR(us);
-		goto fail;
-	}
+	if (IS_ERR(us))
+		return PTR_ERR(us);
+
 	ncm_control_intf.iInterface = us[STRING_CTRL_IDX].id;
 	ncm_data_nop_intf.iInterface = us[STRING_DATA_IDX].id;
 	ncm_data_intf.iInterface = us[STRING_DATA_IDX].id;
@@ -1478,20 +1479,16 @@ static int ncm_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;
 	ncm->ctrl_id = status;
 	ncm_iad_desc.bFirstInterface = status;
 
 	ncm_control_intf.bInterfaceNumber = status;
 	ncm_union_desc.bMasterInterface0 = status;
 
-	if (cdev->use_os_string)
-		f->os_desc_table[0].if_id =
-			ncm_iad_desc.bFirstInterface;
-
 	status = usb_interface_id(c, f);
 	if (status < 0)
-		goto fail;
+		return status;
 	ncm->data_id = status;
 
 	ncm_data_nop_intf.bInterfaceNumber = status;
@@ -1500,35 +1497,31 @@ static int ncm_bind(struct usb_configuration *c, struct usb_function *f)
 
 	ecm_desc.wMaxSegmentSize = cpu_to_le16(ncm_opts->max_segment_size);
 
-	status = -ENODEV;
-
 	/* allocate instance-specific endpoints */
 	ep = usb_ep_autoconfig(cdev->gadget, &fs_ncm_in_desc);
 	if (!ep)
-		goto fail;
+		return -ENODEV;
 	ncm->port.in_ep = ep;
 
 	ep = usb_ep_autoconfig(cdev->gadget, &fs_ncm_out_desc);
 	if (!ep)
-		goto fail;
+		return -ENODEV;
 	ncm->port.out_ep = ep;
 
 	ep = usb_ep_autoconfig(cdev->gadget, &fs_ncm_notify_desc);
 	if (!ep)
-		goto fail;
+		return -ENODEV;
 	ncm->notify = ep;
 
-	status = -ENOMEM;
-
 	/* allocate notification request and buffer */
-	ncm->notify_req = usb_ep_alloc_request(ep, GFP_KERNEL);
-	if (!ncm->notify_req)
-		goto fail;
-	ncm->notify_req->buf = kmalloc(NCM_STATUS_BYTECOUNT, GFP_KERNEL);
-	if (!ncm->notify_req->buf)
-		goto fail;
-	ncm->notify_req->context = ncm;
-	ncm->notify_req->complete = ncm_notify_complete;
+	request = usb_ep_alloc_request(ep, GFP_KERNEL);
+	if (!request)
+		return -ENOMEM;
+	request->buf = kmalloc(NCM_STATUS_BYTECOUNT, GFP_KERNEL);
+	if (!request->buf)
+		return -ENOMEM;
+	request->context = ncm;
+	request->complete = ncm_notify_complete;
 
 	/*
 	 * support all relevant hardware speeds... we expect that when
@@ -1548,7 +1541,7 @@ static int ncm_bind(struct usb_configuration *c, struct usb_function *f)
 	status = usb_assign_descriptors(f, ncm_fs_function, ncm_hs_function,
 			ncm_ss_function, ncm_ss_function);
 	if (status)
-		goto fail;
+		return status;
 
 	/*
 	 * NOTE:  all that is done without knowing or caring about
@@ -1561,23 +1554,18 @@ static int ncm_bind(struct usb_configuration *c, struct usb_function *f)
 
 	hrtimer_setup(&ncm->task_timer, ncm_tx_timeout, CLOCK_MONOTONIC, HRTIMER_MODE_REL_SOFT);
 
+	if (cdev->use_os_string) {
+		os_desc_table[0].os_desc = &ncm_opts->ncm_os_desc;
+		os_desc_table[0].if_id = ncm_iad_desc.bFirstInterface;
+		f->os_desc_table = no_free_ptr(os_desc_table);
+		f->os_desc_n = 1;
+	}
+	ncm->notify_req = no_free_ptr(request);
+
 	DBG(cdev, "CDC Network: IN/%s OUT/%s NOTIFY/%s\n",
 			ncm->port.in_ep->name, ncm->port.out_ep->name,
 			ncm->notify->name);
 	return 0;
-
-fail:
-	kfree(f->os_desc_table);
-	f->os_desc_n = 0;
-
-	if (ncm->notify_req) {
-		kfree(ncm->notify_req->buf);
-		usb_ep_free_request(ncm->notify, ncm->notify_req);
-	}
-
-	ERROR(cdev, "%s: can't bind, err %d\n", f->name, status);
-
-	return status;
 }
 
 static inline struct f_ncm_opts *to_f_ncm_opts(struct config_item *item)

-- 
2.51.0.384.g4c02a37b29-goog

[PATCH 4/6] usb: gadget: f_acm: Refactor bind path to use __free()

[Kuen-Han Tsai]

After an bind/unbind cycle, the acm->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.

Unable to handle kernel NULL pointer dereference at virtual address 0000000000000020
Call trace:
 usb_ep_free_request+0x2c/0xec
 gs_free_req+0x30/0x44
 acm_bind+0x1b8/0x1f4
 usb_add_function+0xcc/0x1f0
 configfs_composite_bind+0x468/0x588
 gadget_bind_driver+0x104/0x270
 really_probe+0x190/0x374
 __driver_probe_device+0xa0/0x12c
 driver_probe_device+0x3c/0x218
 __device_attach_driver+0x14c/0x188
 bus_for_each_drv+0x10c/0x168
 __device_attach+0xfc/0x198
 device_initial_probe+0x14/0x24
 bus_probe_device+0x94/0x11c
 device_add+0x268/0x48c
 usb_add_gadget+0x198/0x28c
 dwc3_gadget_init+0x700/0x858
 __dwc3_set_mode+0x3cc/0x664
 process_scheduled_works+0x1d8/0x488
 worker_thread+0x244/0x334
 kthread+0x114/0x1bc
 ret_from_fork+0x10/0x20

Fixes: 1f1ba11b6494 ("usb gadget: issue notifications from ACM function")
Cc: stable@kernel.org
Signed-off-by: Kuen-Han Tsai <khtsai@google.com>
---
 drivers/usb/gadget/function/f_acm.c | 42 +++++++++++++++++--------------------
 1 file changed, 19 insertions(+), 23 deletions(-)

diff --git a/drivers/usb/gadget/function/f_acm.c b/drivers/usb/gadget/function/f_acm.c
index 7061720b9732e4182b02ac3523d49c8e053176b7..106046e17c4e11253e3257899042ab803f3f2657 100644
--- a/drivers/usb/gadget/function/f_acm.c
+++ b/drivers/usb/gadget/function/f_acm.c
@@ -11,12 +11,15 @@
 
 /* #define VERBOSE_DEBUG */
 
+#include <linux/cleanup.h>
 #include <linux/slab.h>
 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/device.h>
 #include <linux/err.h>
 
+#include <linux/usb/gadget.h>
+
 #include "u_serial.h"
 
 
@@ -613,6 +616,7 @@ acm_bind(struct usb_configuration *c, struct usb_function *f)
 	struct usb_string	*us;
 	int			status;
 	struct usb_ep		*ep;
+	struct usb_request	*request __free(free_usb_request) = NULL;
 
 	/* REVISIT might want instance-specific strings to help
 	 * distinguish instances ...
@@ -630,7 +634,7 @@ acm_bind(struct usb_configuration *c, struct usb_function *f)
 	/* allocate instance-specific interface IDs, and patch descriptors */
 	status = usb_interface_id(c, f);
 	if (status < 0)
-		goto fail;
+		return status;
 	acm->ctrl_id = status;
 	acm_iad_descriptor.bFirstInterface = status;
 
@@ -639,43 +643,41 @@ acm_bind(struct usb_configuration *c, struct usb_function *f)
 
 	status = usb_interface_id(c, f);
 	if (status < 0)
-		goto fail;
+		return status;
 	acm->data_id = status;
 
 	acm_data_interface_desc.bInterfaceNumber = status;
 	acm_union_desc.bSlaveInterface0 = status;
 	acm_call_mgmt_descriptor.bDataInterface = status;
 
-	status = -ENODEV;
-
 	/* allocate instance-specific endpoints */
 	ep = usb_ep_autoconfig(cdev->gadget, &acm_fs_in_desc);
 	if (!ep)
-		goto fail;
+		return -ENODEV;
 	acm->port.in = ep;
 
 	ep = usb_ep_autoconfig(cdev->gadget, &acm_fs_out_desc);
 	if (!ep)
-		goto fail;
+		return -ENODEV;
 	acm->port.out = ep;
 
 	ep = usb_ep_autoconfig(cdev->gadget, &acm_fs_notify_desc);
 	if (!ep)
-		goto fail;
+		return -ENODEV;
 	acm->notify = ep;
 
 	acm_iad_descriptor.bFunctionProtocol = acm->bInterfaceProtocol;
 	acm_control_interface_desc.bInterfaceProtocol = acm->bInterfaceProtocol;
 
 	/* allocate notification */
-	acm->notify_req = gs_alloc_req(ep,
-			sizeof(struct usb_cdc_notification) + 2,
-			GFP_KERNEL);
-	if (!acm->notify_req)
-		goto fail;
+	request = gs_alloc_req(ep,
+			       sizeof(struct usb_cdc_notification) + 2,
+			       GFP_KERNEL);
+	if (!request)
+		return -ENODEV;
 
-	acm->notify_req->complete = acm_cdc_notify_complete;
-	acm->notify_req->context = acm;
+	request->complete = acm_cdc_notify_complete;
+	request->context = acm;
 
 	/* support all relevant hardware speeds... we expect that when
 	 * hardware is dual speed, all bulk-capable endpoints work at
@@ -692,7 +694,9 @@ acm_bind(struct usb_configuration *c, struct usb_function *f)
 	status = usb_assign_descriptors(f, acm_fs_function, acm_hs_function,
 			acm_ss_function, acm_ss_function);
 	if (status)
-		goto fail;
+		return status;
+
+	acm->notify_req = no_free_ptr(request);
 
 	dev_dbg(&cdev->gadget->dev,
 		"acm ttyGS%d: IN/%s OUT/%s NOTIFY/%s\n",
@@ -700,14 +704,6 @@ acm_bind(struct usb_configuration *c, struct usb_function *f)
 		acm->port.in->name, acm->port.out->name,
 		acm->notify->name);
 	return 0;
-
-fail:
-	if (acm->notify_req)
-		gs_free_req(acm->notify, acm->notify_req);
-
-	ERROR(cdev, "%s/%p: can't bind, err %d\n", f->name, f, status);
-
-	return status;
 }
 
 static void acm_unbind(struct usb_configuration *c, struct usb_function *f)

-- 
2.51.0.384.g4c02a37b29-goog

[PATCH 5/6] usb: gadget: f_ecm: Refactor bind path to use __free()

[Kuen-Han Tsai]

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: da741b8c56d6 ("usb ethernet gadget: split CDC Ethernet function")
Cc: stable@kernel.org
Signed-off-by: Kuen-Han Tsai <khtsai@google.com>
---
 drivers/usb/gadget/function/f_ecm.c | 48 ++++++++++++++++---------------------
 1 file changed, 20 insertions(+), 28 deletions(-)

diff --git a/drivers/usb/gadget/function/f_ecm.c b/drivers/usb/gadget/function/f_ecm.c
index 027226325039f0c8eaee27a339513a758c01786b..675d2bc538a45747de601b0fcf2b7b8757642214 100644
--- a/drivers/usb/gadget/function/f_ecm.c
+++ b/drivers/usb/gadget/function/f_ecm.c
@@ -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)

-- 
2.51.0.384.g4c02a37b29-goog

[PATCH 6/6] usb: gadget: f_rndis: Refactor bind path to use __free()

[Kuen-Han Tsai]

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: 45fe3b8e5342 ("usb ethernet gadget: split RNDIS function")
Cc: stable@kernel.org
Signed-off-by: Kuen-Han Tsai <khtsai@google.com>
---
 drivers/usb/gadget/function/f_rndis.c | 85 +++++++++++++++--------------------
 1 file changed, 35 insertions(+), 50 deletions(-)

diff --git a/drivers/usb/gadget/function/f_rndis.c b/drivers/usb/gadget/function/f_rndis.c
index 7cec19d65fb534364127ed7fb8cf83cf3b04defe..7451e7cb7a8523acc9fefa6088e6b273bea2e616 100644
--- a/drivers/usb/gadget/function/f_rndis.c
+++ b/drivers/usb/gadget/function/f_rndis.c
@@ -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)

-- 
2.51.0.384.g4c02a37b29-goog