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Commit cfe919b5 authored by Chuansheng Liu's avatar Chuansheng Liu Committed by Felipe Balbi
Browse files

usb: gadget: return the right length in ffs_epfile_io() 



When the request length is aligned to maxpacketsize, sometimes
the return length ret > the user space requested len.

At that time, we will use min_t(size_t, ret, len) to limit the
size in case of user data buffer overflow.

But we need return the min_t(size_t, ret, len) to tell the user
space rightly also.

[ balbi@ti.com: also fix comment's indentation ]

Acked-by: default avatarMichal Nazarewicz <mina86@mina86.com>
Reviewed-by: default avatarDavid Cohen <david.a.cohen@linux.intel.com>
Signed-off-by: default avatarChuansheng Liu <chuansheng.liu@intel.com>
Signed-off-by: default avatarFelipe Balbi <balbi@ti.com>
parent 8bebbe8d

drivers/usb/gadget/f_fs.c

+15 −13
Original line number Diff line number Diff line
@@ -839,19 +839,21 @@ static ssize_t ffs_epfile_io(struct file *file, struct ffs_io_data *io_data) 
				usb_ep_dequeue(ep->ep, req);

			} else {

				/*

			 * XXX We may end up silently droping data here.

			 * Since data_len (i.e. req->length) may be bigger

			 * than len (after being rounded up to maxpacketsize),

			 * we may end up with more data then user space has

			 * space for.

				 * XXX We may end up silently droping data

				 * here.  Since data_len (i.e. req->length) may

				 * be bigger than len (after being rounded up

				 * to maxpacketsize), we may end up with more

				 * data then user space has space for.

				 */

				ret = ep->status;

			if (io_data->read && ret > 0 &&

			    unlikely(copy_to_user(io_data->buf, data,

						  min_t(size_t, ret,

						  io_data->len))))

				if (io_data->read && ret > 0) {

					ret = min_t(size_t, ret, io_data->len);



					if (unlikely(copy_to_user(io_data->buf,

						data, ret)))

						ret = -EFAULT;

				}

			}

			kfree(data);

		}

	}