staging: ozwpan: prevent overflow in oz_cdev_write()

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

Reported-by: Nico Golde <nico@ngolde.de>
Reported-by: Fabian Yamaguchi <fabs@goesec.de>
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Cc: stable@kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 3 insertions, 0 deletions

diff --git a/drivers/staging/ozwpan/ozcdev.c b/drivers/staging/ozwpan/ozcdev.c
index 6ccb64fb0786..6ce0af9977d8 100644
--- a/drivers/staging/ozwpan/ozcdev.c
+++ b/drivers/staging/ozwpan/ozcdev.c
@@ -155,6 +155,9 @@ static ssize_t oz_cdev_write(struct file *filp, const char __user *buf,
         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)