From c92f8ecfde847edea7778f75c25f05047b770c77 Mon Sep 17 00:00:00 2001
From: Shane Smiskol <shane@smiskol.com>
Date: Fri, 31 Mar 2023 19:17:16 -0700
Subject: [PATCH] IsoTpMessage: fix rx_len sanity checks (#1319)

fix a bug
---
 python/uds.py | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/python/uds.py b/python/uds.py
index 9fd179cc..4fbff043 100644
--- a/python/uds.py
+++ b/python/uds.py
@@ -460,7 +460,7 @@ class IsoTpMessage():
     # single rx_frame
     if rx_data[0] >> 4 == 0x0:
       self.rx_len = rx_data[0] & 0xFF
-      assert self.rx_len <= 0x7, f"isotp - rx: invalid single frame length: {self.rx_len}"
+      assert self.rx_len < self.max_len, f"isotp - rx: invalid single frame length: {self.rx_len}"
       self.rx_dat = rx_data[1:1 + self.rx_len]
       self.rx_idx = 0
       self.rx_done = True
@@ -470,7 +470,7 @@ class IsoTpMessage():
     # first rx_frame
     elif rx_data[0] >> 4 == 0x1:
       self.rx_len = ((rx_data[0] & 0x0F) << 8) + rx_data[1]
-      assert 0x8 <= self.rx_len, f"isotp - rx: invalid first frame length: {self.rx_len}"
+      assert self.max_len <= self.rx_len, f"isotp - rx: invalid first frame length: {self.rx_len}"
       self.rx_dat = rx_data[2:]
       self.rx_idx = 0
       self.rx_done = False