[PATCH v2] usb: gadget: f_fs: Fix use after free issue as part of queue failure

* [PATCH v2] usb: gadget: f_fs: Fix use after free issue as part of queue failure
@ 2020-03-26 11:56 Sriharsha Allenki
  2020-03-27 15:03 ` Sasha Levin
  0 siblings, 1 reply; 2+ messages in thread
From: Sriharsha Allenki @ 2020-03-26 11:56 UTC (permalink / raw)
  To: balbi, gregkh, linux-usb
  Cc: peter.chen, stable, mgautam, jackp, Sriharsha Allenki

In AIO case, the request is freed up if ep_queue fails.
However, io_data->req still has the reference to this freed
request. In the case of this failure if there is aio_cancel
call on this io_data it will lead to an invalid dequeue
operation and a potential use after free issue.
Fix this by setting the io_data->req to NULL when the request
is freed as part of queue failure.

Fixes: 2e4c7553cd6f ("usb: gadget: f_fs: add aio support")
Signed-off-by: Sriharsha Allenki <sallenki@codeaurora.org>
CC: stable <stable@vger.kernel.org>
Reviewed-by: Peter Chen <peter.chen@nxp.com>
---
Changes in v2:
	- As suggested by Greg, updated the tags

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

diff --git a/drivers/usb/gadget/function/f_fs.c b/drivers/usb/gadget/function/f_fs.c
index 571917677d35..767f30b86645 100644
--- a/drivers/usb/gadget/function/f_fs.c
+++ b/drivers/usb/gadget/function/f_fs.c
@@ -1120,6 +1120,7 @@ static ssize_t ffs_epfile_io(struct file *file, struct ffs_io_data *io_data)
 
 		ret = usb_ep_queue(ep->ep, req, GFP_ATOMIC);
 		if (unlikely(ret)) {
+			io_data->req = NULL;
 			usb_ep_free_request(ep->ep, req);
 			goto error_lock;
 		}
-- 
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