1 files changed, 34 insertions, 8 deletions

diff --git a/drivers/usb/gadget/function/f_fs.c b/drivers/usb/gadget/function/f_fs.c
index 7c6771d027a2..63314ede7ba6 100644
--- a/drivers/usb/gadget/function/f_fs.c
+++ b/drivers/usb/gadget/function/f_fs.c
@@ -647,15 +647,26 @@ static void ffs_user_copy_worker(struct work_struct *work)
 	if (io_data->read && ret > 0) {
 		int i;
 		size_t pos = 0;
+
+		/*
+		 * Since req->length may be bigger than io_data->len (after
+		 * being rounded up to maxpacketsize), we may end up with more
+		 * data then user space has space for.
+		 */
+		ret = min_t(int, ret, io_data->len);
+
 		use_mm(io_data->mm);
 		for (i = 0; i < io_data->nr_segs; i++) {
+			size_t len = min_t(size_t, ret - pos,
+					io_data->iovec[i].iov_len);
+			if (!len)
+				break;
 			if (unlikely(copy_to_user(io_data->iovec[i].iov_base,
-						 &io_data->buf[pos],
-						 io_data->iovec[i].iov_len))) {
+						 &io_data->buf[pos], len))) {
 				ret = -EFAULT;
 				break;
 			}
-			pos += io_data->iovec[i].iov_len;
+			pos += len;
 		}
 		unuse_mm(io_data->mm);
 	}
@@ -687,7 +698,7 @@ static ssize_t ffs_epfile_io(struct file *file, struct ffs_io_data *io_data)
 	struct ffs_epfile *epfile = file->private_data;
 	struct ffs_ep *ep;
 	char *data = NULL;
-	ssize_t ret, data_len;
+	ssize_t ret, data_len = -EINVAL;
 	int halt;
 
 	/* Are we still active? */
@@ -787,13 +798,30 @@ static ssize_t ffs_epfile_io(struct file *file, struct ffs_io_data *io_data)
 		/* Fire the request */
 		struct usb_request *req;
 
+		/*
+		 * Sanity Check: even though data_len can't be used
+		 * uninitialized at the time I write this comment, some
+		 * compilers complain about this situation.
+		 * In order to keep the code clean from warnings, data_len is
+		 * being initialized to -EINVAL during its declaration, which
+		 * means we can't rely on compiler anymore to warn no future
+		 * changes won't result in data_len being used uninitialized.
+		 * For such reason, we're adding this redundant sanity check
+		 * here.
+		 */
+		if (unlikely(data_len == -EINVAL)) {
+			WARN(1, "%s: data_len == -EINVAL\n", __func__);
+			ret = -EINVAL;
+			goto error_lock;
+		}
+
 		if (io_data->aio) {
 			req = usb_ep_alloc_request(ep->ep, GFP_KERNEL);
 			if (unlikely(!req))
 				goto error_lock;
 
 			req->buf      = data;
-			req->length   = io_data->len;
+			req->length   = data_len;
 
 			io_data->buf = data;
 			io_data->ep = ep->ep;
@@ -815,7 +843,7 @@ static ssize_t ffs_epfile_io(struct file *file, struct ffs_io_data *io_data)
 
 			req = ep->req;
 			req->buf      = data;
-			req->length   = io_data->len;
+			req->length   = data_len;
 
 			req->context  = &done;
 			req->complete = ffs_epfile_io_complete;
@@ -2663,8 +2691,6 @@ static inline struct f_fs_opts *ffs_do_functionfs_bind(struct usb_function *f,
 	func->conf = c;
 	func->gadget = c->cdev->gadget;
 
-	ffs_data_get(func->ffs);
-
 	/*
 	 * in drivers/usb/gadget/configfs.c:configfs_composite_bind()
 	 * configurations are bound in sequence with list_for_each_entry,