patch 9.0.0225: using freed memory with multiple line breaks in expressionv9.0.0225

Problem:    Using freed memory with multiple line breaks in expression.
Solution:   Free eval_tofree later.

1 files changed, 60 insertions, 42 deletions

diff --git a/src/eval.c b/src/eval.c
index 42b883e9b0..60daca51ce 100644
--- a/src/eval.c
+++ b/src/eval.c
@@ -354,6 +354,63 @@ eval_to_string_skip(
 }
 
 /*
+ * Initialize "evalarg" for use.
+ */
+    void
+init_evalarg(evalarg_T *evalarg)
+{
+    CLEAR_POINTER(evalarg);
+    ga_init2(&evalarg->eval_tofree_ga, sizeof(char_u *), 20);
+}
+
+/*
+ * If "evalarg->eval_tofree" is not NULL free it later.
+ * Caller is expected to overwrite "evalarg->eval_tofree" next.
+ */
+    static void
+free_eval_tofree_later(evalarg_T *evalarg)
+{
+    if (evalarg->eval_tofree != NULL)
+    {
+	if (ga_grow(&evalarg->eval_tofree_ga, 1) == OK)
+	    ((char_u **)evalarg->eval_tofree_ga.ga_data)
+		[evalarg->eval_tofree_ga.ga_len++]
+		= evalarg->eval_tofree;
+	else
+	    vim_free(evalarg->eval_tofree);
+    }
+}
+
+/*
+ * After using "evalarg" filled from "eap": free the memory.
+ */
+    void
+clear_evalarg(evalarg_T *evalarg, exarg_T *eap)
+{
+    if (evalarg != NULL)
+    {
+	if (evalarg->eval_tofree != NULL)
+	{
+	    if (eap != NULL)
+	    {
+		// We may need to keep the original command line, e.g. for
+		// ":let" it has the variable names.  But we may also need the
+		// new one, "nextcmd" points into it.  Keep both.
+		vim_free(eap->cmdline_tofree);
+		eap->cmdline_tofree = *eap->cmdlinep;
+		*eap->cmdlinep = evalarg->eval_tofree;
+	    }
+	    else
+		vim_free(evalarg->eval_tofree);
+	    evalarg->eval_tofree = NULL;
+	}
+
+	ga_clear_strings(&evalarg->eval_tofree_ga);
+	VIM_CLEAR(evalarg->eval_tofree_lambda);
+    }
+}
+
+/*
  * Skip over an expression at "*pp".
  * Return FAIL for an error, OK otherwise.
  */
@@ -435,8 +492,8 @@ skip_expr_concatenate(
 		// Do not free the first line, the caller can still use it.
 		*((char_u **)gap->ga_data) = NULL;
 		// Do not free the last line, "arg" points into it, free it
-		// later.
-		vim_free(evalarg->eval_tofree);
+		// later.  Also free "eval_tofree" later if needed.
+		free_eval_tofree_later(evalarg);
 		evalarg->eval_tofree =
 				    ((char_u **)gap->ga_data)[gap->ga_len - 1];
 		((char_u **)gap->ga_data)[gap->ga_len - 1] = NULL;
@@ -2274,7 +2331,7 @@ eval_next_line(char_u *arg, evalarg_T *evalarg)
     }
     else if (evalarg->eval_cookie != NULL)
     {
-	vim_free(evalarg->eval_tofree);
+	free_eval_tofree_later(evalarg);
 	evalarg->eval_tofree = line;
     }
 
@@ -2302,45 +2359,6 @@ skipwhite_and_linebreak(char_u *arg, evalarg_T *evalarg)
 }
 
 /*
- * Initialize "evalarg" for use.
- */
-    void
-init_evalarg(evalarg_T *evalarg)
-{
-    CLEAR_POINTER(evalarg);
-    ga_init2(&evalarg->eval_tofree_ga, sizeof(char_u *), 20);
-}
-
-/*
- * After using "evalarg" filled from "eap": free the memory.
- */
-    void
-clear_evalarg(evalarg_T *evalarg, exarg_T *eap)
-{
-    if (evalarg != NULL)
-    {
-	if (evalarg->eval_tofree != NULL)
-	{
-	    if (eap != NULL)
-	    {
-		// We may need to keep the original command line, e.g. for
-		// ":let" it has the variable names.  But we may also need the
-		// new one, "nextcmd" points into it.  Keep both.
-		vim_free(eap->cmdline_tofree);
-		eap->cmdline_tofree = *eap->cmdlinep;
-		*eap->cmdlinep = evalarg->eval_tofree;
-	    }
-	    else
-		vim_free(evalarg->eval_tofree);
-	    evalarg->eval_tofree = NULL;
-	}
-
-	ga_clear_strings(&evalarg->eval_tofree_ga);
-	VIM_CLEAR(evalarg->eval_tofree_lambda);
-    }
-}
-
-/*
  * The "evaluate" argument: When FALSE, the argument is only parsed but not
  * executed.  The function may return OK, but the rettv will be of type
  * VAR_UNKNOWN.  The function still returns FAIL for a syntax error.