dm snapshot: optimize track_chunk

[firefly-linux-kernel-4.4.55.git] / drivers / md / dm-ioctl.c

diff --git a/drivers/md/dm-ioctl.c b/drivers/md/dm-ioctl.c
index afd95986d09903a11652aafe8e90912db9f356ca..a651d528f80d14d5a27bd5a563686a1567897eef 100644 (file)
--- a/drivers/md/dm-ioctl.c
+++ b/drivers/md/dm-ioctl.c
@@ -1566,6 +1566,14 @@ static int copy_params(struct dm_ioctl __user *user, struct dm_ioctl **param)
        if (copy_from_user(dmi, user, tmp.data_size))
                goto bad;
 
+       /*
+        * Abort if something changed the ioctl data while it was being copied.
+        */
+       if (dmi->data_size != tmp.data_size) {
+               DMERR("rejecting ioctl: data size modified while processing parameters");
+               goto bad;
+       }
+
        /* Wipe the user buffer so we do not return it to userspace */
        if (secure_data && clear_user(user, tmp.data_size))
                goto bad;