[PATCH 1/2] usb: chipidea: udc: improve error handling on ep_queue

[eu@felipetonello.com]

From: "Felipe F. Tonello" <eu@felipetonello.com>

_ep_queue() didn't check for errors when using add_td_to_list()
which can fail if dma_pool_alloc fails, thus causing a kernel
panic when lastnode->ptr is NULL.

Signed-off-by: Felipe F. Tonello <eu@felipetonello.com>
---
 drivers/usb/chipidea/udc.c | 26 +++++++++++++++++++-------
 1 file changed, 19 insertions(+), 7 deletions(-)

diff --git a/drivers/usb/chipidea/udc.c b/drivers/usb/chipidea/udc.c
index 764f668..7169113e 100644
--- a/drivers/usb/chipidea/udc.c
+++ b/drivers/usb/chipidea/udc.c
@@ -404,9 +404,9 @@ static inline u8 _usb_addr(struct ci_hw_ep *ep)
 }
 
 /**
- * _hardware_queue: configures a request at hardware level
- * @gadget: gadget
+ * _hardware_enqueue: configures a request at hardware level
  * @hwep:   endpoint
+ * @hwreq:  request
  *
  * This function returns an error code
  */
@@ -435,19 +435,27 @@ static int _hardware_enqueue(struct ci_hw_ep *hwep, struct ci_hw_req *hwreq)
 	if (hwreq->req.dma % PAGE_SIZE)
 		pages--;
 
-	if (rest == 0)
-		add_td_to_list(hwep, hwreq, 0);
+	if (rest == 0) {
+		ret = add_td_to_list(hwep, hwreq, 0);
+		if (ret < 0)
+			goto done;
+	}
 
 	while (rest > 0) {
 		unsigned count = min(hwreq->req.length - hwreq->req.actual,
 					(unsigned)(pages * CI_HDRC_PAGE_SIZE));
-		add_td_to_list(hwep, hwreq, count);
+		ret = add_td_to_list(hwep, hwreq, count);
+		if (ret < 0)
+			goto done;
 		rest -= count;
 	}
 
 	if (hwreq->req.zero && hwreq->req.length
-	    && (hwreq->req.length % hwep->ep.maxpacket == 0))
-		add_td_to_list(hwep, hwreq, 0);
+	    && (hwreq->req.length % hwep->ep.maxpacket == 0)) {
+		ret = add_td_to_list(hwep, hwreq, 0);
+		if (ret < 0)
+			goto done;
+	}
 
 	firstnode = list_first_entry(&hwreq->tds, struct td_node, td);
 
@@ -750,8 +758,12 @@ static void isr_get_status_complete(struct usb_ep *ep, struct usb_request *req)
 
 /**
  * _ep_queue: queues (submits) an I/O request to an endpoint
+ * @ep:        endpoint
+ * @req:       request
+ * @gfp_flags: GFP flags (not used)
  *
  * Caller must hold lock
+ * This function returns an error code
  */
 static int _ep_queue(struct usb_ep *ep, struct usb_request *req,
 		    gfp_t __maybe_unused gfp_flags)
-- 
2.1.4