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Subject[PATCH 3.16 027/346] usb: renesas_usbhs: fix NULL pointer dereference in xfer_work()
3.16.39-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>

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>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
drivers/usb/renesas_usbhs/fifo.c | 18 ++++++++++++++----
1 file changed, 14 insertions(+), 4 deletions(-)

--- a/drivers/usb/renesas_usbhs/fifo.c
+++ b/drivers/usb/renesas_usbhs/fifo.c
@@ -780,27 +780,34 @@ static void xfer_work(struct work_struct
{
struct usbhs_pkt *pkt = container_of(work, struct usbhs_pkt, work);
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 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_transfer_direction dir;
+ 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_DEV_TO_MEM : DMA_MEM_TO_DEV;

desc = dmaengine_prep_slave_single(chan, pkt->dma + pkt->actual,
pkt->trans, dir,
DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
if (!desc)
- return;
+ goto xfer_work_end;

desc->callback = usbhsf_dma_complete;
desc->callback_param = pipe;

if (dmaengine_submit(desc) < 0) {
dev_err(dev, "Failed to submit dma descriptor\n");
- return;
+ goto xfer_work_end;
}

dev_dbg(dev, " %s %d (%d/ %d)\n",
@@ -810,6 +817,9 @@ static void xfer_work(struct work_struct
usbhs_pipe_set_trans_count_if_bulk(pipe, pkt->trans);
dma_async_issue_pending(chan);
usbhs_pipe_enable(pipe);
+
+xfer_work_end:
+ usbhs_unlock(priv, flags);
}

/*
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