Re: [PATCH v2] usbip: Fix free of unallocated memory in vhci tx

[Julia Lawall]

On Tue, 22 Oct 2019, Suwan Kim wrote:

> iso_buffer should be set to NULL after use and free in the while loop.
> In the case of isochronous URB in the while loop, iso_buffer is
> allocated and after sending it to server, buffer is deallocated. And
> then, if the next URB in the while loop is not a isochronous pipe,
> iso_buffer still holds the previously deallocated buffer address and
> kfree tries to free wrong buffer address.
>
> Fixes: ea44d190764b ("usbip: Implement SG support to vhci-hcd and stub driver")
> Reported-by: kbuild test robot <lkp@xxxxxxxxx>
> Reported-by: Julia Lawall <julia.lawall@xxxxxxx>
> Signed-off-by: Suwan Kim <suwan.kim027@xxxxxxxxx>

Reviewed-by: Julia Lawall <julia.lawall@xxxxxxx>

> ---
> v1 - v2: Move the setting NULL after kfree() and add the comment
> ---
>  drivers/usb/usbip/vhci_tx.c | 3 +++
>  1 file changed, 3 insertions(+)
>
> diff --git a/drivers/usb/usbip/vhci_tx.c b/drivers/usb/usbip/vhci_tx.c
> index c3803785f6ef..0ae40a13a9fe 100644
> --- a/drivers/usb/usbip/vhci_tx.c
> +++ b/drivers/usb/usbip/vhci_tx.c
> @@ -147,7 +147,10 @@ static int vhci_send_cmd_submit(struct vhci_device *vdev)
>  		}
>
>  		kfree(iov);
> +		/* This is only for isochronous case */
>  		kfree(iso_buffer);
> +		iso_buffer = NULL;
> +
>  		usbip_dbg_vhci_tx("send txdata\n");
>
>  		total_size += txsize;
> --
> 2.20.1
>
>