composite_dev_cleanup call from the failure of configfs_composite_bind
frees up the cdev->os_desc_req and cdev->req. If the previous calls of
bind and unbind is successful these will carry stale values.
Consider the below sequence of function calls:
configfs_composite_bind()
composite_dev_prepare()
- Allocate cdev->req, cdev->req->buf
composite_os_desc_req_prepare()
- Allocate cdev->os_desc_req, cdev->os_desc_req->buf
configfs_composite_unbind()
composite_dev_cleanup()
- free the cdev->os_desc_req->buf and cdev->req->buf
Next composition switch
configfs_composite_bind()
- If it fails goto err_comp_cleanup will call the
composite_dev_cleanup() function
composite_dev_cleanup()
- calls kfree up with the stale values of cdev->req->buf and
cdev->os_desc_req from the previous configfs_composite_bind
call. The free call on these stale values leads to double free.
Hence, Fix this issue by setting request and buffer pointer to NULL after
kfree.
Signed-off-by: Chandana Kishori Chiluveru <cchiluve@xxxxxxxxxxxxxx>
Changes in v2:
- Modified commit text.
---
drivers/usb/gadget/composite.c | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/drivers/usb/gadget/composite.c b/drivers/usb/gadget/composite.c
index b8a1584..992f1e2 100644
--- a/drivers/usb/gadget/composite.c
+++ b/drivers/usb/gadget/composite.c
@@ -2155,14 +2155,18 @@ void composite_dev_cleanup(struct usb_composite_dev *cdev)
usb_ep_dequeue(cdev->gadget->ep0, cdev->os_desc_req);
kfree(cdev->os_desc_req->buf);
+ cdev->os_desc_req->buf = NULL;
usb_ep_free_request(cdev->gadget->ep0, cdev->os_desc_req);
+ cdev->os_desc_req = NULL;
}
if (cdev->req) {
if (cdev->setup_pending)
usb_ep_dequeue(cdev->gadget->ep0, cdev->req);
kfree(cdev->req->buf);
+ cdev->req->buf = NULL;
usb_ep_free_request(cdev->gadget->ep0, cdev->req);
+ cdev->req = NULL;
}
cdev->next_string_id = 0;
device_remove_file(&cdev->gadget->dev, &dev_attr_suspended);
--
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