[PATCH] Fix NULL pointer dereference on firmware name for early calls to get_drvinfo.

[PATCH] Fix NULL pointer dereference on firmware name for early calls to get_drvinfo.

[Bill Nottingham]

The driver comments show an initialization sequence of:
 * i2400m_setup()
 *   i2400m->bus_setup()
 *   i2400m_bootrom_init()
 *   register_netdev()
 *   wimax_dev_add()
 *   i2400m_dev_start()
 *     __i2400m_dev_start()
 *       i2400m_dev_bootstrap()

dev_bootstrap() is where the firmware is loaded. So, if something calls
get_drvinfo() from a register_netdevice_notifier (such as the cnic driver),
we won't have a firmware name, and strncpy will crash.

https://bugzilla.redhat.com/show_bug.cgi?id=808603

Signed-off-by: Bill Nottingham <notting@redhat.com>
---
 drivers/net/wimax/i2400m/netdev.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/net/wimax/i2400m/netdev.c b/drivers/net/wimax/i2400m/netdev.c
index 63e4b70..e44f4e2 100644
--- a/drivers/net/wimax/i2400m/netdev.c
+++ b/drivers/net/wimax/i2400m/netdev.c
@@ -597,7 +597,8 @@ static void i2400m_get_drvinfo(struct net_device *net_dev,
 	struct i2400m *i2400m = net_dev_to_i2400m(net_dev);
 
 	strncpy(info->driver, KBUILD_MODNAME, sizeof(info->driver) - 1);
-	strncpy(info->fw_version, i2400m->fw_name, sizeof(info->fw_version) - 1);
+	if (i2400m->fw_name)
+		strncpy(info->fw_version, i2400m->fw_name, sizeof(info->fw_version) - 1);
 	if (net_dev->dev.parent)
 		strncpy(info->bus_info, dev_name(net_dev->dev.parent),
 			sizeof(info->bus_info) - 1);
-- 
1.7.9.3

Re: [PATCH] Fix NULL pointer dereference on firmware name for early calls to get_drvinfo.

[David Miller]

From: Bill Nottingham <notting@redhat.com>
Date: Fri, 30 Mar 2012 16:24:05 -0400

> The driver comments show an initialization sequence of:
>  * i2400m_setup()
>  *   i2400m->bus_setup()
>  *   i2400m_bootrom_init()
>  *   register_netdev()
>  *   wimax_dev_add()
>  *   i2400m_dev_start()
>  *     __i2400m_dev_start()
>  *       i2400m_dev_bootstrap()
> 
> dev_bootstrap() is where the firmware is loaded. So, if something calls
> get_drvinfo() from a register_netdevice_notifier (such as the cnic driver),
> we won't have a firmware name, and strncpy will crash.
> 
> https://bugzilla.redhat.com/show_bug.cgi?id=808603
> 
> Signed-off-by: Bill Nottingham <notting@redhat.com>

Already fixed in current sources.