usb: renesas_usbhs: fix NULL pointer dereference in xfer_work()

commit 4fdef698383db07d829da567e0e405fc41ff3a89 upstream.

This patch fixes an issue that the xfer_work() is possible to cause
NULL pointer dereference if the usb cable is disconnected while data
transfer is running.

In such case, a gadget driver may call usb_ep_disable()) before
xfer_work() is actually called. In this case, the usbhs_pkt_pop()
will call usbhsf_fifo_unselect(), and then usbhs_pipe_to_fifo()
in xfer_work() will return NULL.

Fixes: e73a989 ("usb: renesas_usbhs: add DMAEngine support")
Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>
[bwh: Backported to 3.2: adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

diff --git a/drivers/usb/renesas_usbhs/fifo.c b/drivers/usb/renesas_usbhs/fifo.c
index 6fb5514..2eb39b3 100644 (file)
--- a/drivers/usb/renesas_usbhs/fifo.c
+++ b/drivers/usb/renesas_usbhs/fifo.c
@@ -760,15 +760,22 @@ static void usbhsf_dma_prepare_tasklet(unsigned long data)
 {
        struct usbhs_pkt *pkt = (struct usbhs_pkt *)data;
        struct usbhs_pipe *pipe = pkt->pipe;
-       struct usbhs_fifo *fifo = usbhs_pipe_to_fifo(pipe);
+       struct usbhs_fifo *fifo;
        struct usbhs_priv *priv = usbhs_pipe_to_priv(pipe);
        struct scatterlist sg;
        struct dma_async_tx_descriptor *desc;
-       struct dma_chan *chan = usbhsf_dma_chan_get(fifo, pkt);
+       struct dma_chan *chan;
        struct device *dev = usbhs_priv_to_dev(priv);
        enum dma_data_direction dir;
        dma_cookie_t cookie;
+       unsigned long flags;
+
+       usbhs_lock(priv, flags);
+       fifo = usbhs_pipe_to_fifo(pipe);
+       if (!fifo)
+               goto xfer_work_end;
 
+       chan = usbhsf_dma_chan_get(fifo, pkt);
        dir = usbhs_pipe_is_dir_in(pipe) ? DMA_FROM_DEVICE : DMA_TO_DEVICE;
 
        sg_init_table(&sg, 1);
@@ -781,7 +788,7 @@ static void usbhsf_dma_prepare_tasklet(unsigned long data)
                                                  DMA_PREP_INTERRUPT |
                                                  DMA_CTRL_ACK);
        if (!desc)
-               return;
+               goto xfer_work_end;
 
        desc->callback          = usbhsf_dma_complete;
        desc->callback_param    = pipe;
@@ -789,7 +796,7 @@ static void usbhsf_dma_prepare_tasklet(unsigned long data)
        cookie = desc->tx_submit(desc);
        if (cookie < 0) {
                dev_err(dev, "Failed to submit dma descriptor\n");
-               return;
+               goto xfer_work_end;
        }
 
        dev_dbg(dev, "  %s %d (%d/ %d)\n",
@@ -797,6 +804,9 @@ static void usbhsf_dma_prepare_tasklet(unsigned long data)
 
        usbhsf_dma_start(pipe, fifo);
        dma_async_issue_pending(chan);
+
+xfer_work_end:
+       usbhs_unlock(priv, flags);
 }
 
 /*