vim-patch:9.0.2109: [security]: overflow in nv_z_get_count

Problem:  [security]: overflow in nv_z_get_count
Solution: break out, if count is too large

When getting the count for a normal z command, it may overflow for large
counts given. So verify, that we can safely store the result in a long.

58f9befca1

Co-authored-by: Christian Brabandt <cb@256bit.org>

src/nvim/normal.c

@@ -2695,6 +2695,10 @@ static bool nv_z_get_count(cmdarg_T *cap, int *nchar_arg)
     if (nchar == K_DEL || nchar == K_KDEL) {
       n /= 10;
     } else if (ascii_isdigit(nchar)) {
+      if (n > INT_MAX / 10) {
+        clearopbeep(cap->oap);
+        break;
+      }
       n = n * 10 + (nchar - '0');
     } else if (nchar == CAR) {
       win_setheight(n);

test/old/testdir/test_normal.vim

@@ -4164,4 +4164,9 @@ func Test_normal33_g_cmd_nonblank()
   bw!
 endfunc
 
+func Test_normal34_zet_large()
+  " shouldn't cause overflow
+  norm! z9765405999999999999
+endfunc
+
 " vim: shiftwidth=2 sts=2 expandtab