From 7e206a90db1254222be56053dc136b344160b937 Mon Sep 17 00:00:00 2001
From: alrvid <126816223+alrvid@users.noreply.github.com>
Date: Wed, 14 Jun 2023 23:29:38 +0200
Subject: [PATCH] Handle negative values passed to close()

Calling close() with negative numbers causes out-of-bounds indexing of the filehandles array. For example, this can happen if open() returns an error and the value is later passed to close().
---
 platform/source/mbed_retarget.cpp | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/platform/source/mbed_retarget.cpp b/platform/source/mbed_retarget.cpp
index cf6dd3c0b7..8bbe9e7d61 100644
--- a/platform/source/mbed_retarget.cpp
+++ b/platform/source/mbed_retarget.cpp
@@ -656,6 +656,11 @@ extern "C" int PREFIX(_close)(FILEHANDLE fh)
 #if !MBED_CONF_PLATFORM_STDIO_MINIMAL_CONSOLE_ONLY
 extern "C" int close(int fildes)
 {
+    if (fildes < 0)
+    {
+        errno = EBADF;
+        return -1;
+    }
     FileHandle *fhc = mbed_file_handle(fildes);
     filehandles[fildes] = NULL;
     if (fhc == NULL) {