Re: [PATCH net,v2] wifi: mac80211: fix general-protection-fault in ieee80211_subif_start_xmit()

[shaozhengchao <shaozhengchao@huawei.com>]

On 2022/10/26 13:46, Ping-Ke Shih wrote:
> 
> 
>> -----Original Message-----
>> From: Zhengchao Shao <shaozhengchao@huawei.com>
>> Sent: Wednesday, October 26, 2022 10:47 AM
>> To: linux-wireless@vger.kernel.org; netdev@vger.kernel.org; johannes@sipsolutions.net;
>> davem@davemloft.net; edumazet@google.com; kuba@kernel.org; pabeni@redhat.com
>> Cc: toke@kernel.org; alexander@wetzel-home.de; nbd@nbd.name; weiyongjun1@huawei.com;
>> yuehaibing@huawei.com; shaozhengchao@huawei.com
>> Subject: [PATCH net,v2] wifi: mac80211: fix general-protection-fault in ieee80211_subif_start_xmit()
>>
>> When device is running and the interface status is changed, the gpf issue
>> is triggered. The problem triggering process is as follows:
>> Thread A:                           Thread B
>> ieee80211_runtime_change_iftype()   process_one_work()
>>      ...                                 ...
>>      ieee80211_do_stop()                 ...
>>      ...                                 ...
>>          sdata->bss = NULL               ...
>>          ...                             ieee80211_subif_start_xmit()
>>                                              ieee80211_multicast_to_unicast
>>                                      //!sdata->bss->multicast_to_unicast
>>                                        cause gpf issue
>>
>> When the interface status is changed, the sending queue continues to send
>> packets. After the bss is set to NULL, the bss is accessed. As a result,
>> this causes a general-protection-fault issue.
>>
>> The following is the stack information:
>> general protection fault, probably for non-canonical address
>> 0xdffffc000000002f: 0000 [#1] PREEMPT SMP KASAN
>> KASAN: null-ptr-deref in range [0x0000000000000178-0x000000000000017f]
>> Workqueue: mld mld_ifc_work
>> RIP: 0010:ieee80211_subif_start_xmit+0x25b/0x1310
>> Call Trace:
>> <TASK>
>> dev_hard_start_xmit+0x1be/0x990
>> __dev_queue_xmit+0x2c9a/0x3b60
>> ip6_finish_output2+0xf92/0x1520
>> ip6_finish_output+0x6af/0x11e0
>> ip6_output+0x1ed/0x540
>> mld_sendpack+0xa09/0xe70
>> mld_ifc_work+0x71c/0xdb0
>> process_one_work+0x9bf/0x1710
>> worker_thread+0x665/0x1080
>> kthread+0x2e4/0x3a0
>> ret_from_fork+0x1f/0x30
>> </TASK>
>>
>> Fixes: f856373e2f31 ("wifi: mac80211: do not wake queues on a vif that is being stopped")
>> Reported-by: syzbot+c6e8fca81c294fd5620a@syzkaller.appspotmail.com
>> Signed-off-by: Zhengchao Shao <shaozhengchao@huawei.com>
>> ---
>>   net/mac80211/tx.c | 5 +++++
>>   1 file changed, 5 insertions(+)
>>
>> diff --git a/net/mac80211/tx.c b/net/mac80211/tx.c
>> index a364148149f9..c38485f39d2b 100644
>> --- a/net/mac80211/tx.c
>> +++ b/net/mac80211/tx.c
>> @@ -4418,6 +4418,11 @@ netdev_tx_t ieee80211_subif_start_xmit(struct sk_buff *skb,
>>   	if (likely(!is_multicast_ether_addr(eth->h_dest)))
>>   		goto normal;
>>
>> +	if (unlikely(!ieee80211_sdata_running(sdata))) {
>> +                kfree_skb(skb);
>> +                return NETDEV_TX_OK;
>> +        }
>> +
> 
> The indent looks odd. It seems like you use spaces instead of tabs?
> 
Hi Shih:
	Thank you for your review. I will fix it in V3.

Zhengchao Shao
>>   	if (unlikely(ieee80211_multicast_to_unicast(skb, dev))) {
>>   		struct sk_buff_head queue;
>>
>> --
>> 2.17.1
>>
>>
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>