Re: [PATCH v2 2/2] usb: cdns3: fix memory double free when handle zero packet

[Roger Quadros]

On 02/02/2024 17:42, Frank Li wrote:
> 829  if (request->complete) {
> 830          spin_unlock(&priv_dev->lock);
> 831          usb_gadget_giveback_request(&priv_ep->endpoint,
> 832                                    request);
> 833          spin_lock(&priv_dev->lock);
> 834  }
> 835
> 836  if (request->buf == priv_dev->zlp_buf)
> 837      cdns3_gadget_ep_free_request(&priv_ep->endpoint, request);
> 
> Driver append an additional zero packet request when queue a packet, which
> length mod max packet size is 0. When transfer complete, run to line 831,
> usb_gadget_giveback_request() will free this requestion. 836 condition is
> true, so cdns3_gadget_ep_free_request() free this request again.
> 
> Log:
> 
> [ 1920.140696][  T150] BUG: KFENCE: use-after-free read in cdns3_gadget_giveback+0x134/0x2c0 [cdns3]
> [ 1920.140696][  T150]
> [ 1920.151837][  T150] Use-after-free read at 0x000000003d1cd10b (in kfence-#36):
> [ 1920.159082][  T150]  cdns3_gadget_giveback+0x134/0x2c0 [cdns3]
> [ 1920.164988][  T150]  cdns3_transfer_completed+0x438/0x5f8 [cdns3]
> 
> Add check at line 829, skip call usb_gadget_giveback_request() if it is
> additional zero length packet request. Needn't call
> usb_gadget_giveback_request() because it is allocated in this driver.
> 
> Cc: <stable@xxxxxxxxxxxxxxx>
> Fixes: 7733f6c32e36 ("usb: cdns3: Add Cadence USB3 DRD Driver")
> Signed-off-by: Frank Li <Frank.Li@xxxxxxx>

Reviewed-by: Roger Quadros <rogerq@xxxxxxxxxx>