diff --git a/sys/compat/svr4/svr4_stream.c b/sys/compat/svr4/svr4_stream.c
index 68bdf7c38684..e11c84cfaee4 100644
--- a/sys/compat/svr4/svr4_stream.c
+++ b/sys/compat/svr4/svr4_stream.c
@@ -2226,6 +2226,8 @@ svr4_do_getmsg(td, uap, fp)
 	}
 
 	if (uap->ctl) {
+		if (ctl.len > sizeof(sc))
+			ctl.len = sizeof(sc);
 		if (ctl.len != -1)
 			if ((error = copyout(&sc, ctl.buf, ctl.len)) != 0)
 				return error;