linux-kernel - [PATCH] orangefs: handle zero size write in debugfs

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Message-ID: <20170414191153.GB30875@mwanda>
Date:   Fri, 14 Apr 2017 22:11:53 +0300
From:   Dan Carpenter <dan.carpenter@...cle.com>
To:     Mike Marshall <hubcap@...ibond.com>
Cc:     linux-kernel@...r.kernel.org, kernel-janitors@...r.kernel.org
Subject: [PATCH] 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@...cle.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...