This is a note to let you know that I've just added the patch titled usb: usbip: set buffer pointers to NULL after free to the 4.9-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: usb-usbip-set-buffer-pointers-to-null-after-free.patch and it can be found in the queue-4.9 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From b3b51417d0af63fb9a06662dc292200aed9ea53f Mon Sep 17 00:00:00 2001 From: Michael Grzeschik <m.grzeschik@xxxxxxxxxxxxxx> Date: Mon, 22 May 2017 13:02:44 +0200 Subject: usb: usbip: set buffer pointers to NULL after free From: Michael Grzeschik <m.grzeschik@xxxxxxxxxxxxxx> commit b3b51417d0af63fb9a06662dc292200aed9ea53f upstream. The usbip stack dynamically allocates the transfer_buffer and setup_packet of each urb that got generated by the tcp to usb stub code. As these pointers are always used only once we will set them to NULL after use. This is done likewise to the free_urb code in vudc_dev.c. This patch fixes double kfree situations where the usbip remote side added the URB_FREE_BUFFER. Signed-off-by: Michael Grzeschik <m.grzeschik@xxxxxxxxxxxxxx> Acked-by: Shuah Khan <shuahkh@xxxxxxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- drivers/usb/usbip/stub_main.c | 4 ++++ drivers/usb/usbip/stub_tx.c | 4 ++++ 2 files changed, 8 insertions(+) --- a/drivers/usb/usbip/stub_main.c +++ b/drivers/usb/usbip/stub_main.c @@ -262,7 +262,11 @@ void stub_device_cleanup_urbs(struct stu kmem_cache_free(stub_priv_cache, priv); kfree(urb->transfer_buffer); + urb->transfer_buffer = NULL; + kfree(urb->setup_packet); + urb->setup_packet = NULL; + usb_free_urb(urb); } } --- a/drivers/usb/usbip/stub_tx.c +++ b/drivers/usb/usbip/stub_tx.c @@ -28,7 +28,11 @@ static void stub_free_priv_and_urb(struc struct urb *urb = priv->urb; kfree(urb->setup_packet); + urb->setup_packet = NULL; + kfree(urb->transfer_buffer); + urb->transfer_buffer = NULL; + list_del(&priv->list); kmem_cache_free(stub_priv_cache, priv); usb_free_urb(urb); Patches currently in stable-queue which might be from m.grzeschik@xxxxxxxxxxxxxx are queue-4.9/usb-usbip-set-buffer-pointers-to-null-after-free.patch