jim tcl: prevent expr stack overflow

expr-prevent-stack-overflow.patch

From c57bc5d040d03301de1d75dc77c1ea4d9ca0f7db Mon Sep 17 00:00:00 2001
From: Steve Bennett <steveb@workware.net.au>
Date: Thu, 18 Jan 2018 08:41:24 +1000
Subject: [PATCH] expr: prevent stack overflow

Limit the depth of the expressions to a reasonable level to prevent
stack overflow

Signed-off-by: Steve Bennett <steveb@workware.net.au>
---
 jim.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/jim.c b/jim.c
index 7de75e65..9ae90636 100644
--- a/jim.c
+++ b/jim.c
@@ -8830,7 +8830,10 @@ static int ExprTreeBuildTree(Jim_Interp *interp, struct ExprBuilder *builder, in
     /* Calculate the stack length expected after pushing the number of expected terms */
     int exp_stacklen = builder->stack.len + exp_numterms;
 
-    builder->level++;
+    if (builder->level++ > 200) {
+        Jim_SetResultString(interp, "Expression too complex", -1);
+        return JIM_ERR;
+    }
 
     while (builder->token->type != JIM_TT_EOL) {
         ParseToken *t = builder->token++;
-- 
2.13.5 (Apple Git-94)