diff options
| author | Chandana Kishori Chiluveru <cchiluve@codeaurora.org> | 2019-10-01 13:16:48 +0530 |
|---|---|---|
| committer | Felipe Balbi <balbi@kernel.org> | 2019-10-27 08:58:45 +0200 |
| commit | 1c20c89b0421b52b2417bb0f62a611bc669eda1d (patch) | |
| tree | d0e073b1b40b0b32147daacc25239e45799103d6 /drivers/usb/gadget/composite.c | |
| parent | ba3a1a915c49cc3023e4ddfc88f21e7514e82aa4 (diff) | |
| download | lwn-1c20c89b0421b52b2417bb0f62a611bc669eda1d.tar.gz lwn-1c20c89b0421b52b2417bb0f62a611bc669eda1d.zip | |
usb: gadget: composite: Fix possible double free memory bug
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@codeaurora.org>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>
Diffstat (limited to 'drivers/usb/gadget/composite.c')
| -rw-r--r-- | drivers/usb/gadget/composite.c | 4 |
1 files changed, 4 insertions, 0 deletions
diff --git a/drivers/usb/gadget/composite.c b/drivers/usb/gadget/composite.c index d516e8d6cd7f..5ec54b69c29c 100644 --- a/drivers/usb/gadget/composite.c +++ b/drivers/usb/gadget/composite.c @@ -2170,14 +2170,18 @@ 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); |