From 3cf08662ea51a1a7ea344b450896be12e4605931 Mon Sep 17 00:00:00 2001
From: Giovanni Di Sirio <gdisirio@gmail.com>
Date: Wed, 9 Feb 2022 13:11:26 +0000
Subject: [PATCH] Fixed invalid root handling by the VFS streams driver.

git-svn-id: svn://svn.code.sf.net/p/chibios/svn/trunk@15455 27425a3e-05d8-49a3-a47f-9c15f0e5edd8
---
 os/vfs/drivers/overlay/drvoverlay.c | 9 ++++++---
 os/vfs/drivers/streams/drvstreams.c | 9 ++++++++-
 2 files changed, 14 insertions(+), 4 deletions(-)

diff --git a/os/vfs/drivers/overlay/drvoverlay.c b/os/vfs/drivers/overlay/drvoverlay.c
index 54da09e0a..c8b248368 100644
--- a/os/vfs/drivers/overlay/drvoverlay.c
+++ b/os/vfs/drivers/overlay/drvoverlay.c
@@ -222,7 +222,7 @@ static msg_t open_absolute_dir(vfs_overlay_driver_c *drvp,
       if (!CH_RET_IS_ERROR(ret)) {
         /* Delegating node creation to a registered driver.*/
         ret = dp->vmt->open_dir((void *)dp,
-                                scanpath,
+                                *scanpath == '\0' ? "/" : scanpath,
                                 vdnpp);
       }
       else {
@@ -285,8 +285,11 @@ static msg_t open_absolute_file(vfs_overlay_driver_c *drvp,
       /* Searching for a match among registered overlays.*/
       ret = match_driver(drvp, &scanpath, &dp);
       if (!CH_RET_IS_ERROR(ret)) {
-        /* Delegating node creation to a registered driver.*/
-        ret = dp->vmt->open_file((void *)dp, scanpath, oflag, vfnpp);
+        /* Delegating node creation to a registered driver, making sure it
+           does not receive an empty path.*/
+        ret = dp->vmt->open_file((void *)dp,
+                                 *scanpath == '\0' ? "/" : scanpath,
+                                 oflag, vfnpp);
       }
       else {
         /* Is there an overlaid driver? if so we need to pass request
diff --git a/os/vfs/drivers/streams/drvstreams.c b/os/vfs/drivers/streams/drvstreams.c
index 6e3a52108..143fcd3cf 100644
--- a/os/vfs/drivers/streams/drvstreams.c
+++ b/os/vfs/drivers/streams/drvstreams.c
@@ -204,9 +204,16 @@ static msg_t drv_open_file(void *instance,
     err = vfs_parse_match_separator(&path);
     CH_BREAK_ON_ERROR(err);
 
-    err = path_get_element(&path, fname, VFS_CFG_NAMELEN_MAX + 1);
+    err = (msg_t)path_get_element(&path, fname, VFS_CFG_NAMELEN_MAX + 1);
     CH_BREAK_ON_ERROR(err);
 
+    /* Null element.*/
+    if (err == (msg_t)0) {
+      /* Trying to open the root as a file.*/
+      err = CH_RET_EISDIR;
+      break;
+    }
+
     err = vfs_parse_match_end(&path);
     CH_BREAK_ON_ERROR(err);