On Thu, Jan 5, 2017 at 9:33 AM, David Miller <da...@davemloft.net> wrote:
> From: Wang Yufen <wangyu...@huawei.com>
> Date: Thu, 5 Jan 2017 22:13:21 +0800
>
>> From: Yufen Wang <wangyu...@huawei.com>
>>
>> A possible NULL pointer dereference in tg3_get_stats64 while doing
>> tg3_free_consistent.
> ...
>> This patch avoids the NULL pointer dereference by using !tg3_flag(tp,
>> INIT_COMPLETE)
>> instate of !tp->hw_stats.
>>
>> Signed-off-by: Yufen Wang <wangyu...@huawei.com>
>> ---
>> drivers/net/ethernet/broadcom/tg3.c | 2 +-
>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/drivers/net/ethernet/broadcom/tg3.c
>> b/drivers/net/ethernet/broadcom/tg3.c
>> index 185e9e0..012f18d 100644
>> --- a/drivers/net/ethernet/broadcom/tg3.c
>> +++ b/drivers/net/ethernet/broadcom/tg3.c
>> @@ -14148,7 +14148,7 @@ static struct rtnl_link_stats64
>> *tg3_get_stats64(struct net_device *dev,
>> struct tg3 *tp = netdev_priv(dev);
>>
>> spin_lock_bh(&tp->lock);
>> - if (!tp->hw_stats) {
>> + if (!tg3_flag(tp, INIT_COMPLETE)) {
>
> The real issue is the manner and order in which the driver performs
> initialization actions relative to netif_device_{attach,detach}().
>
> That is what needs to be fixed here, instead of adding more and more
> ad-hoc tests to the various methods which can be invoked once the
> netif_device_attach() occurs.
Normally, ndo_get_stats64() should be under rtnl lock in the netlink
code path and we should be safe. We only free tp->hw_stats under rtnl
lock in the close path or ethtool path.
But it looks like ndo_get_stats() can be called without rtnl lock from
net-procfs.c. So it is possible that we'll read tp->hw_stats after it
has been freed. For example, if we are reading /proc/net/dev and
closing tg3 at the same time. David, is not taking rtnl_lock in
net-procfs.c by design?
