BUG/MINOR: hlua: fix leak in hlua_ckch_set() error path

in hlua_ckch_commit_yield() and hlua_ckch_set(), when an error occurs,
we enter the error path and try to raise an error from the <err> msg
pointer which must be freed afterwards.

However, the fact that luaL_error() never returns was overlooked, because
of that <err> msg is never freed in such case.

To fix the issue, let's use hlua_pushfstring_safe() helper to push the
err on the lua stack and then free it before throwing the error using
lua_error().

It should be backported up to 2.6 with 30fcca1 ("MINOR: ssl/lua:
CertCache.set() allows to update an SSL certificate file")

(cherry picked from commit 755c2da)
Signed-off-by: Amaury Denoyelle <[email protected]>

Author: Darlelet

src/hlua.c

@@ -13143,8 +13143,9 @@ __LJMP static int hlua_ckch_commit_yield(lua_State *L, int status, lua_KContext
 error:
 	ckch_store_free(new_ckchs);
 	HA_SPIN_UNLOCK(CKCH_LOCK, &ckch_lock);
-	WILL_LJMP(luaL_error(L, "%s", err));
+	hlua_pushfstring_safe(L, "%s", err);
 	free(err);
+	WILL_LJMP(lua_error(L));
 
 	return 0;
 }
@@ -13287,7 +13288,9 @@ __LJMP static int hlua_ckch_set(lua_State *L)
 
 	if (errcode & ERR_CODE) {
 		ckch_store_free(new_ckchs);
-		WILL_LJMP(luaL_error(L, "%s", err));
+		hlua_pushfstring_safe(L, "%s", err);
+		free(err);
+		WILL_LJMP(lua_error(L));
 	}
 	free(err);