From: Dan Carpenter <dan.carpenter@oracle.com>
Date: Fri, 14 Apr 2017 19:11:53 +0000 (+0300)
Subject: orangefs: handle zero size write in debugfs
X-Git-Tag: v4.12-rc1~89^2~3
X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;ds=sidebyside;h=907bfcd8d8a616ca794ba187f6bf1b0e12b3a8dd;p=karo-tx-linux.git

orangefs: handle zero size write in debugfs

If we write zero bytes to this debugfs file, then it will cause an
underflow when we do copy_from_user(buf, ubuf, count - 1).  Debugfs can
normally only be written to by root so the impact of this is low.

Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Mike Marshall <hubcap@omnibond.com>
---

diff --git a/fs/orangefs/orangefs-debugfs.c b/fs/orangefs/orangefs-debugfs.c
index 791912da97d7..716ed337f166 100644
--- a/fs/orangefs/orangefs-debugfs.c
+++ b/fs/orangefs/orangefs-debugfs.c
@@ -440,6 +440,9 @@ static ssize_t orangefs_debug_write(struct file *file,
 		"orangefs_debug_write: %pD\n",
 		file);
 
+	if (count == 0)
+		return 0;
+
 	/*
 	 * Thwart users who try to jamb a ridiculous number
 	 * of bytes into the debug file...