vim-patch:8.0.1475: invalid memory access in read_redo()

Problem:    Invalid memory access in read_redo(). (gy741)
Solution:   Convert the replacement character back from a negative number to
            CR or NL. (hint by Dominique Pelle, closes vim/vim#2616)

f12519dec8

src/nvim/normal.c

@@ -1641,12 +1641,20 @@ void do_pending_operator(cmdarg_T *cap, int old_col, bool gui_yank)
           prep_redo(oap->regname, cap->count0,
               get_op_char(oap->op_type), get_extra_op_char(oap->op_type),
               oap->motion_force, cap->cmdchar, cap->nchar);
-        else if (cap->cmdchar != ':')
+        else if (cap->cmdchar != ':') {
+          int nchar = oap->op_type == OP_REPLACE ? cap->nchar : NUL;
+
+          // reverse what nv_replace() did
+          if (nchar == REPLACE_CR_NCHAR) {
+            nchar = CAR;
+          } else if (nchar == REPLACE_NL_NCHAR) {
+            nchar = NL;
+          }
           prep_redo(oap->regname, 0L, NUL, 'v',
               get_op_char(oap->op_type),
               get_extra_op_char(oap->op_type),
-              oap->op_type == OP_REPLACE
+              nchar);
-              ? cap->nchar : NUL);
+        }
         if (!redo_VIsual_busy) {
           redo_VIsual_mode = resel_VIsual_mode;
           redo_VIsual_vcol = resel_VIsual_vcol;
@@ -5854,10 +5862,13 @@ static void nv_replace(cmdarg_T *cap)
     if (got_int)
       reset_VIsual();
     if (had_ctrl_v) {
-      if (cap->nchar == '\r')
+      // Use a special (negative) number to make a difference between a
-        cap->nchar = -1;
+      // literal CR or NL and a line break.
-      else if (cap->nchar == '\n')
+      if (cap->nchar == CAR) {
-        cap->nchar = -2;
+        cap->nchar = REPLACE_CR_NCHAR;
+      } else if (cap->nchar == NL) {
+        cap->nchar = REPLACE_NL_NCHAR;
+      }
     }
     nv_operator(cap);
     return;

src/nvim/ops.c

@@ -1629,13 +1629,18 @@ int op_replace(oparg_T *oap, int c)
   colnr_T oldlen;
   struct block_def bd;
   char_u              *after_p = NULL;
-  int had_ctrl_v_cr = (c == -1 || c == -2);
+  int had_ctrl_v_cr = false;
 
   if ((curbuf->b_ml.ml_flags & ML_EMPTY ) || oap->empty)
     return OK;              /* nothing to do */
 
-  if (had_ctrl_v_cr)
+  if (c == REPLACE_CR_NCHAR) {
-    c = (c == -1 ? '\r' : '\n');
+    had_ctrl_v_cr = true;
+    c = CAR;
+  } else if (c == REPLACE_NL_NCHAR) {
+    had_ctrl_v_cr = true;
+    c = NL;
+  }
 
   if (has_mbyte)
     mb_adjust_opend(oap);
@@ -1713,7 +1718,7 @@ int op_replace(oparg_T *oap, int c)
       // insert pre-spaces
       memset(newp + bd.textcol, ' ', (size_t)bd.startspaces);
       // insert replacement chars CHECK FOR ALLOCATED SPACE
-      // -1/-2 is used for entering CR literally.
+      // REPLACE_CR_NCHAR/REPLACE_NL_NCHAR is used for entering CR literally.
       size_t after_p_len = 0;
       if (had_ctrl_v_cr || (c != '\r' && c != '\n')) {
           // strlen(newp) at this point

src/nvim/testdir/test_undo.vim

@@ -282,3 +282,10 @@ func Test_cmd_in_reg_undo()
   only!
   let @a=''
 endfunc
+
+func Test_redo_empty_line()
+  new
+  exe "norm\x16r\x160"
+  exe "norm."
+  bwipe!
+endfunc

src/nvim/vim.h

@@ -313,4 +313,8 @@ enum { FOLD_TEXT_LEN = 51 };  //!< buffer size for get_foldtext()
 # define OPEN_CHR_FILES
 #endif
 
+// Replacement for nchar used by nv_replace().
+#define REPLACE_CR_NCHAR    -1
+#define REPLACE_NL_NCHAR    -2
+
 #endif  // NVIM_VIM_H