diff mbox series

ath9k: hif_usb: fix memory leak in ath9k_hif_usb_firmware_cb

Message ID 20210709084351.2087311-1-mudongliangabcd@gmail.com
State New
Headers show
Series ath9k: hif_usb: fix memory leak in ath9k_hif_usb_firmware_cb | expand

Commit Message

Dongliang Mu July 9, 2021, 8:43 a.m. UTC
The commit 03fb92a432ea ("ath9k: hif_usb: fix race condition between
usb_get_urb() and usb_kill_anchored_urbs()") adds three usb_get_urb
in ath9k_hif_usb_dealloc_tx_urbs and usb_free_urb.

Fix this bug by adding corresponding usb_free_urb in
ath9k_hif_usb_dealloc_tx_urbs other and hif_usb_stop.

Reported-by: syzbot+6692c72009680f7c4eb2@syzkaller.appspotmail.com
Fixes: 03fb92a432ea ("ath9k: hif_usb: fix race condition between usb_get_urb() and usb_kill_anchored_urbs()")
Signed-off-by: Dongliang Mu <mudongliangabcd@gmail.com>
---
 drivers/net/wireless/ath/ath9k/hif_usb.c | 3 +++
 1 file changed, 3 insertions(+)

Comments

Dongliang Mu July 23, 2021, 10:12 a.m. UTC | #1
On Fri, Jul 9, 2021 at 4:44 PM Dongliang Mu <mudongliangabcd@gmail.com> wrote:
>
> The commit 03fb92a432ea ("ath9k: hif_usb: fix race condition between
> usb_get_urb() and usb_kill_anchored_urbs()") adds three usb_get_urb
> in ath9k_hif_usb_dealloc_tx_urbs and usb_free_urb.
>
> Fix this bug by adding corresponding usb_free_urb in
> ath9k_hif_usb_dealloc_tx_urbs other and hif_usb_stop.
>

Any idea about this patch?

> Reported-by: syzbot+6692c72009680f7c4eb2@syzkaller.appspotmail.com
> Fixes: 03fb92a432ea ("ath9k: hif_usb: fix race condition between usb_get_urb() and usb_kill_anchored_urbs()")
> Signed-off-by: Dongliang Mu <mudongliangabcd@gmail.com>
> ---
>  drivers/net/wireless/ath/ath9k/hif_usb.c | 3 +++
>  1 file changed, 3 insertions(+)
>
> diff --git a/drivers/net/wireless/ath/ath9k/hif_usb.c b/drivers/net/wireless/ath/ath9k/hif_usb.c
> index 860da13bfb6a..bda91ff3289b 100644
> --- a/drivers/net/wireless/ath/ath9k/hif_usb.c
> +++ b/drivers/net/wireless/ath/ath9k/hif_usb.c
> @@ -457,6 +457,7 @@ static void hif_usb_stop(void *hif_handle)
>                 usb_kill_urb(tx_buf->urb);
>                 list_del(&tx_buf->list);
>                 usb_free_urb(tx_buf->urb);
> +               usb_free_urb(tx_buf->urb);
>                 kfree(tx_buf->buf);
>                 kfree(tx_buf);
>                 spin_lock_irqsave(&hif_dev->tx.tx_lock, flags);
> @@ -779,6 +780,7 @@ static void ath9k_hif_usb_dealloc_tx_urbs(struct hif_device_usb *hif_dev)
>                 usb_kill_urb(tx_buf->urb);
>                 list_del(&tx_buf->list);
>                 usb_free_urb(tx_buf->urb);
> +               usb_free_urb(tx_buf->urb);
>                 kfree(tx_buf->buf);
>                 kfree(tx_buf);
>                 spin_lock_irqsave(&hif_dev->tx.tx_lock, flags);
> @@ -797,6 +799,7 @@ static void ath9k_hif_usb_dealloc_tx_urbs(struct hif_device_usb *hif_dev)
>                 usb_kill_urb(tx_buf->urb);
>                 list_del(&tx_buf->list);
>                 usb_free_urb(tx_buf->urb);
> +               usb_free_urb(tx_buf->urb);
>                 kfree(tx_buf->buf);
>                 kfree(tx_buf);
>                 spin_lock_irqsave(&hif_dev->tx.tx_lock, flags);
> --
> 2.25.1
>
Kalle Valo July 27, 2021, 6:02 a.m. UTC | #2
Dongliang Mu <mudongliangabcd@gmail.com> writes:

> The commit 03fb92a432ea ("ath9k: hif_usb: fix race condition between
> usb_get_urb() and usb_kill_anchored_urbs()") adds three usb_get_urb
> in ath9k_hif_usb_dealloc_tx_urbs and usb_free_urb.
>
> Fix this bug by adding corresponding usb_free_urb in
> ath9k_hif_usb_dealloc_tx_urbs other and hif_usb_stop.
>
> Reported-by: syzbot+6692c72009680f7c4eb2@syzkaller.appspotmail.com
> Fixes: 03fb92a432ea ("ath9k: hif_usb: fix race condition between usb_get_urb() and usb_kill_anchored_urbs()")
> Signed-off-by: Dongliang Mu <mudongliangabcd@gmail.com>

In the past there have been so many problems with ath9k syzbot fixes
that I have now a hard time trusting them. Can someone review this in
detail, please?
Julian Calaby July 27, 2021, 7:24 a.m. UTC | #3
Hi Dongliang,

(Drive-by review, I know almost nothing about the code in question)

On Fri, Jul 9, 2021 at 6:47 PM Dongliang Mu <mudongliangabcd@gmail.com> wrote:
>
> The commit 03fb92a432ea ("ath9k: hif_usb: fix race condition between
> usb_get_urb() and usb_kill_anchored_urbs()") adds three usb_get_urb
> in ath9k_hif_usb_dealloc_tx_urbs and usb_free_urb.
>
> Fix this bug by adding corresponding usb_free_urb in
> ath9k_hif_usb_dealloc_tx_urbs other and hif_usb_stop.
>
> Reported-by: syzbot+6692c72009680f7c4eb2@syzkaller.appspotmail.com
> Fixes: 03fb92a432ea ("ath9k: hif_usb: fix race condition between usb_get_urb() and usb_kill_anchored_urbs()")
> Signed-off-by: Dongliang Mu <mudongliangabcd@gmail.com>
> ---
>  drivers/net/wireless/ath/ath9k/hif_usb.c | 3 +++
>  1 file changed, 3 insertions(+)
>
> diff --git a/drivers/net/wireless/ath/ath9k/hif_usb.c b/drivers/net/wireless/ath/ath9k/hif_usb.c
> index 860da13bfb6a..bda91ff3289b 100644
> --- a/drivers/net/wireless/ath/ath9k/hif_usb.c
> +++ b/drivers/net/wireless/ath/ath9k/hif_usb.c
> @@ -457,6 +457,7 @@ static void hif_usb_stop(void *hif_handle)
>                 usb_kill_urb(tx_buf->urb);
>                 list_del(&tx_buf->list);
>                 usb_free_urb(tx_buf->urb);
> +               usb_free_urb(tx_buf->urb);

Ok, so if I'm reading this correctly, before the first usb_free_urb()
call, we have two references to the urb at tx_buf->urb.

Why?

Isn't the better fix here to detangle why there's more than one
reference to it and resolve it that way? This looks like a hack to fix
something much more fundamentally broken.

Thanks,
Kalle Valo July 27, 2021, 12:26 p.m. UTC | #4
Julian Calaby <julian.calaby@gmail.com> writes:

> Hi Dongliang,
>
> (Drive-by review, I know almost nothing about the code in question)
>
> On Fri, Jul 9, 2021 at 6:47 PM Dongliang Mu <mudongliangabcd@gmail.com> wrote:
>>
>> The commit 03fb92a432ea ("ath9k: hif_usb: fix race condition between
>> usb_get_urb() and usb_kill_anchored_urbs()") adds three usb_get_urb
>> in ath9k_hif_usb_dealloc_tx_urbs and usb_free_urb.
>>
>> Fix this bug by adding corresponding usb_free_urb in
>> ath9k_hif_usb_dealloc_tx_urbs other and hif_usb_stop.
>>
>> Reported-by: syzbot+6692c72009680f7c4eb2@syzkaller.appspotmail.com
>> Fixes: 03fb92a432ea ("ath9k: hif_usb: fix race condition between usb_get_urb() and usb_kill_anchored_urbs()")
>> Signed-off-by: Dongliang Mu <mudongliangabcd@gmail.com>
>> ---
>>  drivers/net/wireless/ath/ath9k/hif_usb.c | 3 +++
>>  1 file changed, 3 insertions(+)
>>
>> diff --git a/drivers/net/wireless/ath/ath9k/hif_usb.c b/drivers/net/wireless/ath/ath9k/hif_usb.c
>> index 860da13bfb6a..bda91ff3289b 100644
>> --- a/drivers/net/wireless/ath/ath9k/hif_usb.c
>> +++ b/drivers/net/wireless/ath/ath9k/hif_usb.c
>> @@ -457,6 +457,7 @@ static void hif_usb_stop(void *hif_handle)
>>                 usb_kill_urb(tx_buf->urb);
>>                 list_del(&tx_buf->list);
>>                 usb_free_urb(tx_buf->urb);
>> +               usb_free_urb(tx_buf->urb);
>
> Ok, so if I'm reading this correctly, before the first usb_free_urb()
> call, we have two references to the urb at tx_buf->urb.
>
> Why?
>
> Isn't the better fix here to detangle why there's more than one
> reference to it and resolve it that way? This looks like a hack to fix
> something much more fundamentally broken.

Yeah, this looks very suspicious.

One more thing: also the patch should be tested with real hardware. I'm
worried that people are just trying to fix a syzbot warning and not
really considering how it works in real life. That's why I'm extra
careful with syzbot patches for wireless drivers.
diff mbox series

Patch

diff --git a/drivers/net/wireless/ath/ath9k/hif_usb.c b/drivers/net/wireless/ath/ath9k/hif_usb.c
index 860da13bfb6a..bda91ff3289b 100644
--- a/drivers/net/wireless/ath/ath9k/hif_usb.c
+++ b/drivers/net/wireless/ath/ath9k/hif_usb.c
@@ -457,6 +457,7 @@  static void hif_usb_stop(void *hif_handle)
 		usb_kill_urb(tx_buf->urb);
 		list_del(&tx_buf->list);
 		usb_free_urb(tx_buf->urb);
+		usb_free_urb(tx_buf->urb);
 		kfree(tx_buf->buf);
 		kfree(tx_buf);
 		spin_lock_irqsave(&hif_dev->tx.tx_lock, flags);
@@ -779,6 +780,7 @@  static void ath9k_hif_usb_dealloc_tx_urbs(struct hif_device_usb *hif_dev)
 		usb_kill_urb(tx_buf->urb);
 		list_del(&tx_buf->list);
 		usb_free_urb(tx_buf->urb);
+		usb_free_urb(tx_buf->urb);
 		kfree(tx_buf->buf);
 		kfree(tx_buf);
 		spin_lock_irqsave(&hif_dev->tx.tx_lock, flags);
@@ -797,6 +799,7 @@  static void ath9k_hif_usb_dealloc_tx_urbs(struct hif_device_usb *hif_dev)
 		usb_kill_urb(tx_buf->urb);
 		list_del(&tx_buf->list);
 		usb_free_urb(tx_buf->urb);
+		usb_free_urb(tx_buf->urb);
 		kfree(tx_buf->buf);
 		kfree(tx_buf);
 		spin_lock_irqsave(&hif_dev->tx.tx_lock, flags);