1. In func configfs_composite_bind() -> composite_os_desc_req_prepare():
if kmalloc fails, the pointer cdev->os_desc_req will be freed but not
 set to NULL. Then it will return a failure to the upper-level function.
2. in func configfs_composite_bind() -> composite_dev_cleanup():
it will checks whether cdev->os_desc_req is NULL. If it is not NULL, it
 will attempt to use it.This will lead to a use-after-free issue.

BUG: KASAN: use-after-free in composite_dev_cleanup+0xf4/0x2c0
Read of size 8 at addr 0000004827837a00 by task init/1

CPU: 10 PID: 1 Comm: init Tainted: G           O      5.10.97-oh #1
 kasan_report+0x188/0x1cc
 __asan_load8+0xb4/0xbc
 composite_dev_cleanup+0xf4/0x2c0
 configfs_composite_bind+0x210/0x7ac
 udc_bind_to_driver+0xb4/0x1ec
 usb_gadget_probe_driver+0xec/0x21c
 gadget_dev_desc_UDC_store+0x264/0x27c

Fixes: 37a3a533429e ("usb: gadget: OS Feature Descriptors support")
Signed-off-by: Tao Xue <xuetao09@huawei.com>
---
v2: update Signed-off and commit message
v1: initial submission

 drivers/usb/gadget/composite.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/usb/gadget/composite.c b/drivers/usb/gadget/composite.c
index 8dbc132a505e..385398a039ea 100644
--- a/drivers/usb/gadget/composite.c
+++ b/drivers/usb/gadget/composite.c
@@ -2489,6 +2489,7 @@ int composite_os_desc_req_prepare(struct usb_composite_dev *cdev,
 	if (!cdev->os_desc_req->buf) {
 		ret = -ENOMEM;
 		usb_ep_free_request(ep0, cdev->os_desc_req);
+		cdev->os_desc_req = NULL;
 		goto end;
 	}
 	cdev->os_desc_req->context = cdev;
-- 
2.17.1

On Mon, Jul 21, 2025 at 11:58:49AM +0800, Tao Xue wrote:
> 1. In func configfs_composite_bind() -> composite_os_desc_req_prepare():
> if kmalloc fails, the pointer cdev->os_desc_req will be freed but not
>  set to NULL. Then it will return a failure to the upper-level function.
> 2. in func configfs_composite_bind() -> composite_dev_cleanup():
> it will checks whether cdev->os_desc_req is NULL. If it is not NULL, it
>  will attempt to use it.This will lead to a use-after-free issue.
> 
> BUG: KASAN: use-after-free in composite_dev_cleanup+0xf4/0x2c0
> Read of size 8 at addr 0000004827837a00 by task init/1
> 
> CPU: 10 PID: 1 Comm: init Tainted: G           O      5.10.97-oh #1
>  kasan_report+0x188/0x1cc
>  __asan_load8+0xb4/0xbc
>  composite_dev_cleanup+0xf4/0x2c0
>  configfs_composite_bind+0x210/0x7ac
>  udc_bind_to_driver+0xb4/0x1ec
>  usb_gadget_probe_driver+0xec/0x21c
>  gadget_dev_desc_UDC_store+0x264/0x27c
> 
> Fixes: 37a3a533429e ("usb: gadget: OS Feature Descriptors support")
> Signed-off-by: Tao Xue <xuetao09@huawei.com>
> ---
> v2: update Signed-off and commit message
> v1: initial submission
> 
>  drivers/usb/gadget/composite.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/drivers/usb/gadget/composite.c b/drivers/usb/gadget/composite.c
> index 8dbc132a505e..385398a039ea 100644
> --- a/drivers/usb/gadget/composite.c
> +++ b/drivers/usb/gadget/composite.c
> @@ -2489,6 +2489,7 @@ int composite_os_desc_req_prepare(struct usb_composite_dev *cdev,
>  	if (!cdev->os_desc_req->buf) {
>  		ret = -ENOMEM;
>  		usb_ep_free_request(ep0, cdev->os_desc_req);
> +		cdev->os_desc_req = NULL;

Please add a comment here as to why this must be set to NULL at this
point in time, as it is not obvious at all.

thanks,

greg k-h