1 files changed, 23 insertions, 3 deletions

diff --git a/drivers/usb/gadget/function/f_fs.c b/drivers/usb/gadget/function/f_fs.c
index 002c3441bea3..75912ce6ab55 100644
--- a/drivers/usb/gadget/function/f_fs.c
+++ b/drivers/usb/gadget/function/f_fs.c
@@ -150,6 +150,8 @@ struct ffs_dma_fence {
 	struct dma_fence base;
 	struct ffs_dmabuf_priv *priv;
 	struct work_struct work;
+	struct usb_ep *ep;
+	struct usb_request *req;
 };
 
 struct ffs_epfile {
@@ -619,7 +621,7 @@ static ssize_t ffs_ep0_read(struct file *file, char __user *buf,
 
 		/* unlocks spinlock */
 		ret = __ffs_ep0_queue_wait(ffs, data, len);
-		if ((ret > 0) && (copy_to_user(buf, data, len)))
+		if ((ret > 0) && (copy_to_user(buf, data, ret)))
 			ret = -EFAULT;
 		goto done_mutex;
 
@@ -1385,6 +1387,21 @@ static void ffs_dmabuf_cleanup(struct work_struct *work)
 	struct ffs_dmabuf_priv *priv = dma_fence->priv;
 	struct dma_buf_attachment *attach = priv->attach;
 	struct dma_fence *fence = &dma_fence->base;
+	struct usb_request *req = dma_fence->req;
+	struct usb_ep *ep = dma_fence->ep;
+
+	/*
+	 * eps_lock pairs with the cancel paths so they cannot pass a freed
+	 * req to usb_ep_dequeue().  Only clear if priv->req still names ours;
+	 * a re-queue on the same attachment may have taken that slot.
+	 */
+	spin_lock_irq(&priv->ffs->eps_lock);
+	if (priv->req == req)
+		priv->req = NULL;
+	spin_unlock_irq(&priv->ffs->eps_lock);
+
+	if (ep && req)
+		usb_ep_free_request(ep, req);
 
 	ffs_dmabuf_put(attach);
 	dma_fence_put(fence);
@@ -1414,8 +1431,8 @@ static void ffs_epfile_dmabuf_io_complete(struct usb_ep *ep,
 					  struct usb_request *req)
 {
 	pr_vdebug("FFS: DMABUF transfer complete, status=%d\n", req->status);
+	/* req is freed by ffs_dmabuf_cleanup() under eps_lock. */
 	ffs_dmabuf_signal_done(req->context, req->status);
-	usb_ep_free_request(ep, req);
 }
 
 static const char *ffs_dmabuf_get_driver_name(struct dma_fence *fence)
@@ -1699,6 +1716,10 @@ static int ffs_dmabuf_transfer(struct file *file,
 	usb_req->context  = fence;
 	usb_req->complete = ffs_epfile_dmabuf_io_complete;
 
+	/* ffs_dmabuf_cleanup() frees usb_req via these two fields. */
+	fence->req = usb_req;
+	fence->ep = ep->ep;
+
 	cookie = dma_fence_begin_signalling();
 	ret = usb_ep_queue(ep->ep, usb_req, GFP_ATOMIC);
 	dma_fence_end_signalling(cookie);
@@ -1708,7 +1729,6 @@ static int ffs_dmabuf_transfer(struct file *file,
 	} else {
 		pr_warn("FFS: Failed to queue DMABUF: %d\n", ret);
 		ffs_dmabuf_signal_done(fence, ret);
-		usb_ep_free_request(ep->ep, usb_req);
 	}
 
 	spin_unlock_irq(&epfile->ffs->eps_lock);