patch "usb: renesas_usbhs: fix NULL pointer dereference in xfer_work()" added to usb-next

[<gregkh@linuxfoundation.org>]

This is a note to let you know that I've just added the patch titled

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

to my usb git tree which can be found at
    git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb.git
in the usb-next branch.

The patch will show up in the next release of the linux-next tree
(usually sometime within the next 24 hours during the week.)

The patch will also be merged in the next major kernel release
during the merge window.

If you have any questions about this process, please let me know.


>From 4fdef698383db07d829da567e0e405fc41ff3a89 Mon Sep 17 00:00:00 2001
From: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Date: Wed, 8 Jun 2016 16:32:49 +0900
Subject: usb: renesas_usbhs: fix NULL pointer dereference in xfer_work()

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")
Cc: <stable@vger.kernel.org> # v3.1+
Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>
---
 drivers/usb/renesas_usbhs/fifo.c | 18 ++++++++++++++----
 1 file changed, 14 insertions(+), 4 deletions(-)

diff --git a/drivers/usb/renesas_usbhs/fifo.c b/drivers/usb/renesas_usbhs/fifo.c
index 7be4e7d57ace..280ed5ff021b 100644
--- a/drivers/usb/renesas_usbhs/fifo.c
+++ b/drivers/usb/renesas_usbhs/fifo.c
@@ -810,20 +810,27 @@ static void xfer_work(struct work_struct *work)
 {
 	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;
@@ -831,7 +838,7 @@ static void xfer_work(struct work_struct *work)
 	pkt->cookie = dmaengine_submit(desc);
 	if (pkt->cookie < 0) {
 		dev_err(dev, "Failed to submit dma descriptor\n");
-		return;
+		goto xfer_work_end;
 	}
 
 	dev_dbg(dev, "  %s %d (%d/ %d)\n",
@@ -842,6 +849,9 @@ static void xfer_work(struct work_struct *work)
 	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);
 }
 
 /*
-- 
2.9.0