[sr-dev] git:5.2:71efcfbb: core: ensure index of preprocessor directive conditions is not negative

[Henning Westerholt]

Module: kamailio
Branch: 5.2
Commit: 71efcfbb059e72cb05572ef7d3f58ac2e7dba397
URL: https://github.com/kamailio/kamailio/commit/71efcfbb059e72cb05572ef7d3f58ac2e7dba397

Author: Daniel-Constantin Mierla <miconda at gmail.com>
Committer: Henning Westerholt <hw at skalatan.de>
Date: 2019-09-10T09:52:11+02:00

core: ensure index of preprocessor directive conditions is not negative

- avoid accessing the array at negative index for else processing

(cherry picked from commit 8f6e826576e52270f21c22a7d94b3026cc22c172)

---

Modified: src/core/cfg.lex

---

Diff:  https://github.com/kamailio/kamailio/commit/71efcfbb059e72cb05572ef7d3f58ac2e7dba397.diff
Patch: https://github.com/kamailio/kamailio/commit/71efcfbb059e72cb05572ef7d3f58ac2e7dba397.patch

---

diff --git a/src/core/cfg.lex b/src/core/cfg.lex
index 6a0d23d76f..6aa890f155 100644
--- a/src/core/cfg.lex
+++ b/src/core/cfg.lex
@@ -1922,14 +1922,24 @@ static void pp_ifdef()
 
 static void pp_else()
 {
+	if(pp_sptr==0) {
+		LM_WARN("invalid position for preprocessor directive 'else'"
+				" - at %s line %d\n", (finame)?finame:"cfg", line);
+		return;
+	}
 	pp_ifdef_stack[pp_sptr-1] ^= 1;
 	pp_update_state();
 }
 
 static void pp_endif()
 {
-	pp_sptr--;
 	pp_ifdef_level_update(-1);
+	if(pp_sptr==0) {
+		LM_WARN("invalid position for preprocessor directive 'else'"
+				" - at %s line %d\n", (finame)?finame:"cfg", line);
+		return;
+	}
+	pp_sptr--;
 	pp_update_state();
 }