From 9a755833492a6a81045d987ba44fd7f105d489c3 Mon Sep 17 00:00:00 2001
From: Grissiom <chaos.proton@gmail.com>
Date: Tue, 14 Oct 2014 16:09:10 +0800
Subject: [PATCH] dfs: check for null reference

---
 components/dfs/src/dfs_file.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/components/dfs/src/dfs_file.c b/components/dfs/src/dfs_file.c
index f5619e235..614a34949 100644
--- a/components/dfs/src/dfs_file.c
+++ b/components/dfs/src/dfs_file.c
@@ -335,6 +335,9 @@ int dfs_file_lseek(struct dfs_fd *fd, rt_off_t offset)
 
     if (fd == RT_NULL)
         return -DFS_STATUS_EINVAL;
+    fs = fd->fs;
+    if (fs == RT_NULL)
+        return -DFS_STATUS_EINVAL;
     if (fs->ops->lseek == RT_NULL)
         return -DFS_STATUS_ENOSYS;