| From af4b54a2e5ba18259ff9aac445bf546dd60d037e Mon Sep 17 00:00:00 2001 |
| From: Ian Abbott <abbotti@mev.co.uk> |
| Date: Mon, 15 Apr 2019 12:43:02 +0100 |
| Subject: staging: comedi: ni_usb6501: Fix possible double-free of ->usb_rx_buf |
| |
| From: Ian Abbott <abbotti@mev.co.uk> |
| |
| commit af4b54a2e5ba18259ff9aac445bf546dd60d037e upstream. |
| |
| `ni6501_alloc_usb_buffers()` is called from `ni6501_auto_attach()` to |
| allocate RX and TX buffers for USB transfers. It allocates |
| `devpriv->usb_rx_buf` followed by `devpriv->usb_tx_buf`. If the |
| allocation of `devpriv->usb_tx_buf` fails, it frees |
| `devpriv->usb_rx_buf`, leaving the pointer set dangling, and returns an |
| error. Later, `ni6501_detach()` will be called from the core comedi |
| module code to clean up. `ni6501_detach()` also frees both |
| `devpriv->usb_rx_buf` and `devpriv->usb_tx_buf`, but |
| `devpriv->usb_rx_buf` may have already beed freed, leading to a |
| double-free error. Fix it bu removing the call to |
| `kfree(devpriv->usb_rx_buf)` from `ni6501_alloc_usb_buffers()`, relying |
| on `ni6501_detach()` to free the memory. |
| |
| Signed-off-by: Ian Abbott <abbotti@mev.co.uk> |
| Cc: stable <stable@vger.kernel.org> |
| Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| |
| --- |
| drivers/staging/comedi/drivers/ni_usb6501.c | 4 +--- |
| 1 file changed, 1 insertion(+), 3 deletions(-) |
| |
| --- a/drivers/staging/comedi/drivers/ni_usb6501.c |
| +++ b/drivers/staging/comedi/drivers/ni_usb6501.c |
| @@ -472,10 +472,8 @@ static int ni6501_alloc_usb_buffers(stru |
| |
| size = usb_endpoint_maxp(devpriv->ep_tx); |
| devpriv->usb_tx_buf = kzalloc(size, GFP_KERNEL); |
| - if (!devpriv->usb_tx_buf) { |
| - kfree(devpriv->usb_rx_buf); |
| + if (!devpriv->usb_tx_buf) |
| return -ENOMEM; |
| - } |
| |
| return 0; |
| } |