FAILED: patch "[PATCH] usb: gadget: f_ecm: Refactor bind path to use __free()" failed to apply to 6.6-stable tree

FAILED: patch "[PATCH] usb: gadget: f_ecm: Refactor bind path to use __free()" failed to apply to 6.6-stable tree

[gregkh]

The patch below does not apply to the 6.6-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@vger.kernel.org>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.6.y
git checkout FETCH_HEAD
git cherry-pick -x 42988380ac67c76bb9dff8f77d7ef3eefd50b7b5
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable@vger.kernel.org>' --in-reply-to '2025101641-passcode-sanitizer-19b3@gregkh' --subject-prefix 'PATCH 6.6.y' HEAD^..

Possible dependencies:



thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 42988380ac67c76bb9dff8f77d7ef3eefd50b7b5 Mon Sep 17 00:00:00 2001
From: Kuen-Han Tsai <khtsai@google.com>
Date: Tue, 16 Sep 2025 16:21:36 +0800
Subject: [PATCH] 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: da741b8c56d6 ("usb ethernet gadget: split CDC Ethernet function")
Cc: stable@kernel.org
Signed-off-by: Kuen-Han Tsai <khtsai@google.com>
Link: https://lore.kernel.org/r/20250916-ready-v1-5-4997bf277548@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Link: https://lore.kernel.org/r/20250916-ready-v1-5-4997bf277548@google.com

diff --git a/drivers/usb/gadget/function/f_ecm.c b/drivers/usb/gadget/function/f_ecm.c
index 027226325039..675d2bc538a4 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)

[PATCH 6.6.y 1/3] usb: gadget: Store endpoint pointer in usb_request

[Sasha Levin]

From: Kuen-Han Tsai <khtsai@google.com>

[ Upstream commit bfb1d99d969fe3b892db30848aeebfa19d21f57f ]

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>
Link: https://lore.kernel.org/r/20250916-ready-v1-1-4997bf277548@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Link: https://lore.kernel.org/r/20250916-ready-v1-1-4997bf277548@google.com
Stable-dep-of: 42988380ac67 ("usb: gadget: f_ecm: Refactor bind path to use __free()")
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 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 a4120a25428e5..25bbb7a440ce2 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 75bda0783395a..7bd39747026e4 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
@@ -97,6 +98,7 @@ struct usb_ep;
  */
 
 struct usb_request {
+	struct usb_ep		*ep;
 	void			*buf;
 	unsigned		length;
 	dma_addr_t		dma;
-- 
2.51.0

[PATCH 6.6.y 2/3] usb: gadget: Introduce free_usb_request helper

[Sasha Levin]

From: Kuen-Han Tsai <khtsai@google.com>

[ Upstream commit 201c53c687f2b55a7cc6d9f4000af4797860174b ]

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>
Link: https://lore.kernel.org/r/20250916-ready-v1-2-4997bf277548@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Link: https://lore.kernel.org/r/20250916-ready-v1-2-4997bf277548@google.com
Stable-dep-of: 42988380ac67 ("usb: gadget: f_ecm: Refactor bind path to use __free()")
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 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 7bd39747026e4..aa831e16c3d39 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>
@@ -291,6 +292,28 @@ 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

[PATCH 6.6.y 3/3] usb: gadget: f_ecm: Refactor bind path to use __free()

[Sasha Levin]

From: Kuen-Han Tsai <khtsai@google.com>

[ Upstream commit 42988380ac67c76bb9dff8f77d7ef3eefd50b7b5 ]

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>
Link: https://lore.kernel.org/r/20250916-ready-v1-5-4997bf277548@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Link: https://lore.kernel.org/r/20250916-ready-v1-5-4997bf277548@google.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 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 2afc30de54ce2..7bb63b9e3f78d 100644
--- a/drivers/usb/gadget/function/f_ecm.c
+++ b/drivers/usb/gadget/function/f_ecm.c
@@ -8,12 +8,15 @@
 
 /* #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/etherdevice.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