From mboxrd@z Thu Jan  1 00:00:00 1970
From: Dan Carpenter <dan.carpenter@oracle.com>
Subject: [patch] libertas: potential oops in debugfs
Date: Tue, 29 Oct 2013 22:06:41 +0300
Message-ID: <20131029190641.GB21820@longonot.mountain>
References: <20131025144452.GA28451@ngolde.de>
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Cc: libertas-dev@lists.infradead.org, linux-wireless@vger.kernel.org,
	netdev@vger.kernel.org, security@kernel.org,
	Nico Golde <nico@ngolde.de>, Fabian Yamaguchi <fabs@goesec.de>
To: "John W. Linville" <linville@tuxdriver.com>
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If we do a zero size write then it will oops.  This can only be
triggered by root.

Reported-by: Nico Golde <nico@ngolde.de>
Reported-by: Fabian Yamaguchi <fabs@goesec.de>
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>

diff --git a/drivers/net/wireless/libertas/debugfs.c b/drivers/net/wireless/libertas/debugfs.c
index 668dd27..a148f14 100644
--- a/drivers/net/wireless/libertas/debugfs.c
+++ b/drivers/net/wireless/libertas/debugfs.c
@@ -913,6 +913,9 @@ static ssize_t lbs_debugfs_write(struct file *f, const char __user *buf,
 	char *p2;
 	struct debug_data *d = f->private_data;
 
+	if (cnt == 0)
+		return 0;
+
 	pdata = kmalloc(cnt, GFP_KERNEL);
 	if (pdata == NULL)
 		return 0;