From 0cc0c3d5032208cac84decb3e861c2cdd19a5aeb Mon Sep 17 00:00:00 2001
From: SPRESENSE <41312067+SPRESENSE@users.noreply.github.com>
Date: Wed, 19 May 2021 18:44:52 +0900
Subject: [PATCH] fs/vfs: Fix bug that select() did not return

Fix bug that select() did not return when the nfds argument
was set to a negative value. The specification is that -1 is
set to the return value and EINVAL is set to errno.
---
 fs/vfs/fs_select.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/fs/vfs/fs_select.c b/fs/vfs/fs_select.c
index 5384f7f78d..1a3734aeff 100644
--- a/fs/vfs/fs_select.c
+++ b/fs/vfs/fs_select.c
@@ -90,6 +90,12 @@ int select(int nfds, FAR fd_set *readfds, FAR fd_set *writefds,
 
   enter_cancellation_point();
 
+  if (nfds < 0)
+    {
+      errcode = EINVAL;
+      goto errout;
+    }
+
   /* How many pollfd structures do we need to allocate? */
 
   /* Initialize the descriptor list for poll() */