From 7f424c3e8ddaa0a6a828175b8e4205c1cc0a2a8a Mon Sep 17 00:00:00 2001
From: chao an <anchao.archer@bytedance.com>
Date: Fri, 7 Feb 2025 22:49:17 +0800
Subject: [PATCH] nshlib/builtin: check background task before restore the
 signal

fix crash if:
CONFIG_SCHED_WAITPID=n
CONFIG_SCHED_CHILD_STATUS=y

The old signal will be restored only when sigaction is saved to avoid invaild access.

Signed-off-by: chao an <anchao.archer@bytedance.com>
---
 nshlib/nsh_builtin.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/nshlib/nsh_builtin.c b/nshlib/nsh_builtin.c
index 6ff8f99a6..196220f41 100644
--- a/nshlib/nsh_builtin.c
+++ b/nshlib/nsh_builtin.c
@@ -234,7 +234,13 @@ int nsh_builtin(FAR struct nsh_vtbl_s *vtbl, FAR const char *cmd,
 
           /* Restore the old actions */
 
-          sigaction(SIGCHLD, &old, NULL);
+#  ifndef CONFIG_SCHED_WAITPID
+          if (vtbl->np.np_bg == true)
+#  endif
+            {
+              sigaction(SIGCHLD, &old, NULL);
+            }
+
 #  endif
           struct sched_param sched;
           sched_getparam(ret, &sched);