From 7a8011bb28c0469bff2c9f838aacba2fa2df53e2 Mon Sep 17 00:00:00 2001
From: Eksan0325 <163502586+Eksan0325@users.noreply.github.com>
Date: Fri, 12 Jun 2026 19:47:28 +0800
Subject: [PATCH] fix: Fix NULL dereference in ecx_mbxreceive when mailbox pool
 is empty

Fix segfault in ecx_mbxreceive on exhausted mailbox pool (Issue#948)
---
 src/ec_main.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/src/ec_main.c b/src/ec_main.c
index c8d0335..0d09432 100644
--- a/src/ec_main.c
+++ b/src/ec_main.c
@@ -1671,7 +1671,12 @@ int ecx_mbxreceive(ecx_contextt *context, uint16 slave, ec_mbxbuft **mbx, int ti
       if ((wkc > 0) && ((SMstat & 0x08) > 0)) /* read mailbox available ? */
       {
          mbxro = slavelist->mbx_ro;
-         mbxin = ecx_getmbx(context);
+         mbxin = ecx_getmbx(context);  
+         if (mbxin == NULL)
+         { 
+             *mbx = NULL;   
+             return 0;     
+         }
          mbxh = (ec_mbxheadert *)mbxin;
          do
          {