[PATCH 3.5 28/78] staging: ozwpan: prevent overflow in oz_cdev_write()

[Luis Henriques]

3.5.7.26 -stable review patch.  If anyone has any objections, please let me know.

------------------

From: Dan Carpenter <dan.carpenter at oracle.com>

commit c2c65cd2e14ada6de44cb527e7f1990bede24e15 upstream.

We need to check "count" so we don't overflow the ei->data buffer.

Reported-by: Nico Golde <nico at ngolde.de>
Reported-by: Fabian Yamaguchi <fabs at goesec.de>
Signed-off-by: Dan Carpenter <dan.carpenter at oracle.com>
Signed-off-by: Linus Torvalds <torvalds at linux-foundation.org>
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 drivers/staging/ozwpan/ozcdev.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/staging/ozwpan/ozcdev.c b/drivers/staging/ozwpan/ozcdev.c
index 27325f7..03dcd1b 100644
--- a/drivers/staging/ozwpan/ozcdev.c
+++ b/drivers/staging/ozwpan/ozcdev.c
@@ -150,6 +150,9 @@ ssize_t oz_cdev_write(struct file *filp, const char __user *buf, size_t count,
 	struct oz_app_hdr *app_hdr;
 	struct oz_serial_ctx *ctx;
 
+	if (count > sizeof(ei->data) - sizeof(*elt) - sizeof(*app_hdr))
+		return -EINVAL;
+
 	spin_lock_bh(&g_cdev.lock);
 	pd = g_cdev.active_pd;
 	if (pd)
-- 
1.8.3.2