vim-patch:7.4.2326

Problem:    Illegal memory access when Visual selection starts in invalid
            position. (Dominique Pelle)
Solution:   Correct position when needed.

d5824ce1b5

src/nvim/normal.c

@@ -7831,6 +7831,7 @@ static void get_op_vcol(
 
   // prevent from moving onto a trail byte
   if (has_mbyte) {
+    check_pos(curwin->w_buffer, &oap->end);
     mb_adjustpos(curwin->w_buffer, &oap->end);
   }