diff mbox series

wifi: mac80211: change initialize for sk_buff in ieee80211_tx_dequeue()

Message ID 20221212083607.21536-1-quic_wgong@quicinc.com
State New
Headers show
Series wifi: mac80211: change initialize for sk_buff in ieee80211_tx_dequeue() | expand

Commit Message

Wen Gong Dec. 12, 2022, 8:36 a.m. UTC 
The sk_buff is only set to NULL when initialize, sometimes it will goto
label "begin" after ieee80211_free_txskb(), then it points to a sk_buff
which is already freed. If it run into the "goto out" after arrived to
label "begin", then it will return a sk_buff which is freed, it is a
risk for use-after-free.

Fixes: ded4698b58cb ("mac80211: run late dequeue late tx handlers without holding fq->lock")
Signed-off-by: Wen Gong <quic_wgong@quicinc.com>
---
 net/mac80211/tx.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)


base-commit: 922932ca02191a390f7f52fb6e21c44b50e14025

Comments

Guenter Roeck Jan. 5, 2023, 5:26 a.m. UTC | #1 
On Mon, Dec 12, 2022 at 03:36:07AM -0500, Wen Gong wrote:
> The sk_buff is only set to NULL when initialize, sometimes it will goto
> label "begin" after ieee80211_free_txskb(), then it points to a sk_buff
> which is already freed. If it run into the "goto out" after arrived to
> label "begin", then it will return a sk_buff which is freed, it is a
> risk for use-after-free.
> 
> Fixes: ded4698b58cb ("mac80211: run late dequeue late tx handlers without holding fq->lock")
> Signed-off-by: Wen Gong <quic_wgong@quicinc.com>

I don't see any progress on this patch. Is there a problem with it ?
Did it get lost ?

Thanks,
Guenter

> ---
>  net/mac80211/tx.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> 
> base-commit: 922932ca02191a390f7f52fb6e21c44b50e14025
> 
> diff --git a/net/mac80211/tx.c b/net/mac80211/tx.c
> index 2171cd1ca807..0b23cc9ab9c7 100644
> --- a/net/mac80211/tx.c
> +++ b/net/mac80211/tx.c
> @@ -3776,7 +3776,7 @@ struct sk_buff *ieee80211_tx_dequeue(struct ieee80211_hw *hw,
>  	struct ieee80211_local *local = hw_to_local(hw);
>  	struct txq_info *txqi = container_of(txq, struct txq_info, txq);
>  	struct ieee80211_hdr *hdr;
> -	struct sk_buff *skb = NULL;
> +	struct sk_buff *skb;
>  	struct fq *fq = &local->fq;
>  	struct fq_tin *tin = &txqi->tin;
>  	struct ieee80211_tx_info *info;
> @@ -3790,6 +3790,8 @@ struct sk_buff *ieee80211_tx_dequeue(struct ieee80211_hw *hw,
>  		return NULL;
>  
>  begin:
> +	skb = NULL;
> +
>  	spin_lock_bh(&fq->lock);
>  
>  	if (test_bit(IEEE80211_TXQ_STOP, &txqi->flags) ||
Alexander Wetzel Jan. 9, 2023, 2:05 p.m. UTC | #2 
On 05.01.23 06:26, Guenter Roeck wrote:
> On Mon, Dec 12, 2022 at 03:36:07AM -0500, Wen Gong wrote:
>> The sk_buff is only set to NULL when initialize, sometimes it will goto
>> label "begin" after ieee80211_free_txskb(), then it points to a sk_buff
>> which is already freed. If it run into the "goto out" after arrived to
>> label "begin", then it will return a sk_buff which is freed, it is a
>> risk for use-after-free.
>>
>> Fixes: ded4698b58cb ("mac80211: run late dequeue late tx handlers without holding fq->lock")
>> Signed-off-by: Wen Gong <quic_wgong@quicinc.com>
> 
> I don't see any progress on this patch. Is there a problem with it ?
> Did it get lost ?
> 

Looks ok for me. But I just noticed that my patch
https://patchwork.kernel.org/project/linux-wireless/patch/20221230121850.218810-1-alexander@wetzel-home.de/

should also fix the issue as an unintended side effect.

Alexander

> Thanks,
> Guenter
> 
>> ---
>>   net/mac80211/tx.c | 4 +++-
>>   1 file changed, 3 insertions(+), 1 deletion(-)
>>
>>
>> base-commit: 922932ca02191a390f7f52fb6e21c44b50e14025
>>
>> diff --git a/net/mac80211/tx.c b/net/mac80211/tx.c
>> index 2171cd1ca807..0b23cc9ab9c7 100644
>> --- a/net/mac80211/tx.c
>> +++ b/net/mac80211/tx.c
>> @@ -3776,7 +3776,7 @@ struct sk_buff *ieee80211_tx_dequeue(struct ieee80211_hw *hw,
>>   	struct ieee80211_local *local = hw_to_local(hw);
>>   	struct txq_info *txqi = container_of(txq, struct txq_info, txq);
>>   	struct ieee80211_hdr *hdr;
>> -	struct sk_buff *skb = NULL;
>> +	struct sk_buff *skb;
>>   	struct fq *fq = &local->fq;
>>   	struct fq_tin *tin = &txqi->tin;
>>   	struct ieee80211_tx_info *info;
>> @@ -3790,6 +3790,8 @@ struct sk_buff *ieee80211_tx_dequeue(struct ieee80211_hw *hw,
>>   		return NULL;
>>   
>>   begin:
>> +	skb = NULL;
>> +
>>   	spin_lock_bh(&fq->lock);
>>   
>>   	if (test_bit(IEEE80211_TXQ_STOP, &txqi->flags) ||
Alexander Wetzel Jan. 9, 2023, 2:22 p.m. UTC | #3 
On 09.01.23 15:05, Alexander Wetzel wrote:
> On 05.01.23 06:26, Guenter Roeck wrote:
>> On Mon, Dec 12, 2022 at 03:36:07AM -0500, Wen Gong wrote:
>>> The sk_buff is only set to NULL when initialize, sometimes it will goto
>>> label "begin" after ieee80211_free_txskb(), then it points to a sk_buff
>>> which is already freed. If it run into the "goto out" after arrived to
>>> label "begin", then it will return a sk_buff which is freed, it is a
>>> risk for use-after-free.
>>>
>>> Fixes: ded4698b58cb ("mac80211: run late dequeue late tx handlers 
>>> without holding fq->lock")
>>> Signed-off-by: Wen Gong <quic_wgong@quicinc.com>
>>
>> I don't see any progress on this patch. Is there a problem with it ?
>> Did it get lost ?
>>
> 
> Looks ok for me. But I just noticed that my patch
> https://patchwork.kernel.org/project/linux-wireless/patch/20221230121850.218810-1-alexander@wetzel-home.de/
> 
> should also fix the issue as an unintended side effect.

Sorry that statement was incomplete: It's only fixed when
https://patchwork.kernel.org/project/linux-wireless/patch/20221230121850.218810-1-alexander@wetzel-home.de/
and
https://patchwork.kernel.org/project/linux-wireless/patch/20230106223141.98696-1-alexander@wetzel-home.de/

are applied.
Guenter Roeck Jan. 9, 2023, 3:39 p.m. UTC | #4 
On 1/9/23 06:05, Alexander Wetzel wrote:
> On 05.01.23 06:26, Guenter Roeck wrote:
>> On Mon, Dec 12, 2022 at 03:36:07AM -0500, Wen Gong wrote:
>>> The sk_buff is only set to NULL when initialize, sometimes it will goto
>>> label "begin" after ieee80211_free_txskb(), then it points to a sk_buff
>>> which is already freed. If it run into the "goto out" after arrived to
>>> label "begin", then it will return a sk_buff which is freed, it is a
>>> risk for use-after-free.
>>>
>>> Fixes: ded4698b58cb ("mac80211: run late dequeue late tx handlers without holding fq->lock")
>>> Signed-off-by: Wen Gong <quic_wgong@quicinc.com>
>>
>> I don't see any progress on this patch. Is there a problem with it ?
>> Did it get lost ?
>>
> 
> Looks ok for me. But I just noticed that my patch
> https://patchwork.kernel.org/project/linux-wireless/patch/20221230121850.218810-1-alexander@wetzel-home.de/
> 
> should also fix the issue as an unintended side effect.
> 

Unless I am missing something, there is still a path

begin:
	...
	
	if (unlikely(test_bit(IEEE80211_TXQ_STOP, &txqi->flags)))
  		goto out;
	...
	skb = ...
	...
                         ieee80211_free_txskb(&local->hw, skb);
                         goto begin;

after your patch is applied. Unless the IEEE80211_TXQ_STOP can never be true
after the first iteration I don't see how your patch would fix the problem.

Guenter

> Alexander
> 
>> Thanks,
>> Guenter
>>
>>> ---
>>>   net/mac80211/tx.c | 4 +++-
>>>   1 file changed, 3 insertions(+), 1 deletion(-)
>>>
>>>
>>> base-commit: 922932ca02191a390f7f52fb6e21c44b50e14025
>>>
>>> diff --git a/net/mac80211/tx.c b/net/mac80211/tx.c
>>> index 2171cd1ca807..0b23cc9ab9c7 100644
>>> --- a/net/mac80211/tx.c
>>> +++ b/net/mac80211/tx.c
>>> @@ -3776,7 +3776,7 @@ struct sk_buff *ieee80211_tx_dequeue(struct ieee80211_hw *hw,
>>>       struct ieee80211_local *local = hw_to_local(hw);
>>>       struct txq_info *txqi = container_of(txq, struct txq_info, txq);
>>>       struct ieee80211_hdr *hdr;
>>> -    struct sk_buff *skb = NULL;
>>> +    struct sk_buff *skb;
>>>       struct fq *fq = &local->fq;
>>>       struct fq_tin *tin = &txqi->tin;
>>>       struct ieee80211_tx_info *info;
>>> @@ -3790,6 +3790,8 @@ struct sk_buff *ieee80211_tx_dequeue(struct ieee80211_hw *hw,
>>>           return NULL;
>>>   begin:
>>> +    skb = NULL;
>>> +
>>>       spin_lock_bh(&fq->lock);
>>>       if (test_bit(IEEE80211_TXQ_STOP, &txqi->flags) ||
>
Guenter Roeck Jan. 9, 2023, 3:43 p.m. UTC | #5 
On 1/9/23 06:22, Alexander Wetzel wrote:
> On 09.01.23 15:05, Alexander Wetzel wrote:
>> On 05.01.23 06:26, Guenter Roeck wrote:
>>> On Mon, Dec 12, 2022 at 03:36:07AM -0500, Wen Gong wrote:
>>>> The sk_buff is only set to NULL when initialize, sometimes it will goto
>>>> label "begin" after ieee80211_free_txskb(), then it points to a sk_buff
>>>> which is already freed. If it run into the "goto out" after arrived to
>>>> label "begin", then it will return a sk_buff which is freed, it is a
>>>> risk for use-after-free.
>>>>
>>>> Fixes: ded4698b58cb ("mac80211: run late dequeue late tx handlers without holding fq->lock")
>>>> Signed-off-by: Wen Gong <quic_wgong@quicinc.com>
>>>
>>> I don't see any progress on this patch. Is there a problem with it ?
>>> Did it get lost ?
>>>
>>
>> Looks ok for me. But I just noticed that my patch
>> https://patchwork.kernel.org/project/linux-wireless/patch/20221230121850.218810-1-alexander@wetzel-home.de/
>>
>> should also fix the issue as an unintended side effect.
> 
> Sorry that statement was incomplete: It's only fixed when
> https://patchwork.kernel.org/project/linux-wireless/patch/20221230121850.218810-1-alexander@wetzel-home.de/
> and
> https://patchwork.kernel.org/project/linux-wireless/patch/20230106223141.98696-1-alexander@wetzel-home.de/
> 
> are applied.
> 

Ah, yes. That is indeed correct. Let's just hope those patches will apply (and are
going to be applied) to stable releases since this is a real problem there which
does cause UAF and crashes.

Guenter
diff mbox series

Patch

diff --git a/net/mac80211/tx.c b/net/mac80211/tx.c
index 2171cd1ca807..0b23cc9ab9c7 100644
--- a/net/mac80211/tx.c
+++ b/net/mac80211/tx.c
@@ -3776,7 +3776,7 @@  struct sk_buff *ieee80211_tx_dequeue(struct ieee80211_hw *hw,
 	struct ieee80211_local *local = hw_to_local(hw);
 	struct txq_info *txqi = container_of(txq, struct txq_info, txq);
 	struct ieee80211_hdr *hdr;
-	struct sk_buff *skb = NULL;
+	struct sk_buff *skb;
 	struct fq *fq = &local->fq;
 	struct fq_tin *tin = &txqi->tin;
 	struct ieee80211_tx_info *info;
@@ -3790,6 +3790,8 @@  struct sk_buff *ieee80211_tx_dequeue(struct ieee80211_hw *hw,
 		return NULL;
 
 begin:
+	skb = NULL;
+
 	spin_lock_bh(&fq->lock);
 
 	if (test_bit(IEEE80211_TXQ_STOP, &txqi->flags) ||