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,