The function r8a66597_endpoint_disable() and r8a66597_urb_enqueue() may
be concurrently executed.
The two functions both access a possible shared variable "hep->hcpriv".
This shared variable is freed by r8a66597_endpoint_disable() via the
call path:
r8a66597_endpoint_disable
kfree(hep->hcpriv) (line 1995 in Linux-4.19)
This variable is read by r8a66597_urb_enqueue() via the call path:
r8a66597_urb_enqueue
spin_lock_irqsave(&r8a66597->lock);
init_pipe_info
enable_r8a66597_pipe
pipe = hep->hcpriv (line 802 in Linux-4.19)
The read operation is protected by a spinlock, but the free operation
is not protected by this spinlock, thus a concurrency use-after-free bug
may occur.
To fix this bug, the spin-lock and spin-unlock function calls in
r8a66597_endpoint_disable() are moved to protect the free operation.
Signed-off-by: Jia-Ju Bai <[email protected]>
---
drivers/usb/host/r8a66597-hcd.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/drivers/usb/host/r8a66597-hcd.c b/drivers/usb/host/r8a66597-hcd.c
index 984892dd72f5..1495ce14ad22 100644
--- a/drivers/usb/host/r8a66597-hcd.c
+++ b/drivers/usb/host/r8a66597-hcd.c
@@ -1991,13 +1991,14 @@ static void r8a66597_endpoint_disable(struct usb_hcd *hcd,
return;
pipenum = pipe->info.pipenum;
+ spin_lock_irqsave(&r8a66597->lock, flags);
if (pipenum == 0) {
kfree(hep->hcpriv);
hep->hcpriv = NULL;
+ spin_unlock_irqrestore(&r8a66597->lock, flags);
return;
}
- spin_lock_irqsave(&r8a66597->lock, flags);
pipe_stop(r8a66597, pipe);
pipe_irq_disable(r8a66597, pipenum);
disable_irq_empty(r8a66597, pipenum);
--
2.17.0
On Tue, Dec 18, 2018 at 06:00:20PM +0800, Jia-Ju Bai wrote:
> The function r8a66597_endpoint_disable() and r8a66597_urb_enqueue() may
> be concurrently executed.
> The two functions both access a possible shared variable "hep->hcpriv".
>
> This shared variable is freed by r8a66597_endpoint_disable() via the
> call path:
> r8a66597_endpoint_disable
> kfree(hep->hcpriv) (line 1995 in Linux-4.19)
>
> This variable is read by r8a66597_urb_enqueue() via the call path:
> r8a66597_urb_enqueue
> spin_lock_irqsave(&r8a66597->lock);
> init_pipe_info
> enable_r8a66597_pipe
> pipe = hep->hcpriv (line 802 in Linux-4.19)
>
> The read operation is protected by a spinlock, but the free operation
> is not protected by this spinlock, thus a concurrency use-after-free bug
> may occur.
>
> To fix this bug, the spin-lock and spin-unlock function calls in
> r8a66597_endpoint_disable() are moved to protect the free operation.
>
> Signed-off-by: Jia-Ju Bai <[email protected]>
> ---
> drivers/usb/host/r8a66597-hcd.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/usb/host/r8a66597-hcd.c b/drivers/usb/host/r8a66597-hcd.c
> index 984892dd72f5..1495ce14ad22 100644
> --- a/drivers/usb/host/r8a66597-hcd.c
> +++ b/drivers/usb/host/r8a66597-hcd.c
> @@ -1991,13 +1991,14 @@ static void r8a66597_endpoint_disable(struct usb_hcd *hcd,
> return;
> pipenum = pipe->info.pipenum;
>
> + spin_lock_irqsave(&r8a66597->lock, flags);
Don't you also need the __aquires/__releases markings on this function
in order to properly annotate it, like the rest of the driver has?
Otherwise this seems to look good to me.
thanks,
greg k-h
On 2018/12/18 19:11, Greg KH wrote:
> On Tue, Dec 18, 2018 at 06:00:20PM +0800, Jia-Ju Bai wrote:
>> The function r8a66597_endpoint_disable() and r8a66597_urb_enqueue() may
>> be concurrently executed.
>> The two functions both access a possible shared variable "hep->hcpriv".
>>
>> This shared variable is freed by r8a66597_endpoint_disable() via the
>> call path:
>> r8a66597_endpoint_disable
>> kfree(hep->hcpriv) (line 1995 in Linux-4.19)
>>
>> This variable is read by r8a66597_urb_enqueue() via the call path:
>> r8a66597_urb_enqueue
>> spin_lock_irqsave(&r8a66597->lock);
>> init_pipe_info
>> enable_r8a66597_pipe
>> pipe = hep->hcpriv (line 802 in Linux-4.19)
>>
>> The read operation is protected by a spinlock, but the free operation
>> is not protected by this spinlock, thus a concurrency use-after-free bug
>> may occur.
>>
>> To fix this bug, the spin-lock and spin-unlock function calls in
>> r8a66597_endpoint_disable() are moved to protect the free operation.
>>
>> Signed-off-by: Jia-Ju Bai <[email protected]>
>> ---
>> drivers/usb/host/r8a66597-hcd.c | 3 ++-
>> 1 file changed, 2 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/usb/host/r8a66597-hcd.c b/drivers/usb/host/r8a66597-hcd.c
>> index 984892dd72f5..1495ce14ad22 100644
>> --- a/drivers/usb/host/r8a66597-hcd.c
>> +++ b/drivers/usb/host/r8a66597-hcd.c
>> @@ -1991,13 +1991,14 @@ static void r8a66597_endpoint_disable(struct usb_hcd *hcd,
>> return;
>> pipenum = pipe->info.pipenum;
>>
>> + spin_lock_irqsave(&r8a66597->lock, flags);
> Don't you also need the __aquires/__releases markings on this function
> in order to properly annotate it, like the rest of the driver has?
Okay, thanks for this suggestion :)
I will send a v2 patch.
Best wishes,
Jia-Ju Bai