2016-03-14 19:20:57

by John Keeping

[permalink] [raw]
Subject: [PATCH] usb: dwc2: gadget: avoid null dereference on incomplete transfer

Setting up a gadget with the uac2 function results in:

Unable to handle kernel NULL pointer dereference at virtual address 00000058
...
PC is at dwc2_hsotg_irq+0x7f0/0x908
LR is at dwc2_hsotg_irq+0x4c/0x908
Backtrace:
[<c03cd5fc>] (dwc2_hsotg_irq) from [<c00814fc>] (handle_irq_event_percpu+0x130/0x3ec)
[<c00813cc>] (handle_irq_event_percpu) from [<c0081800>] (handle_irq_event+0x48/0x6c)

In all other loops we already skip endpoints that are null, so do so
here as well.

Signed-off-by: John Keeping <[email protected]>
---
drivers/usb/dwc2/gadget.c | 8 ++++++--
1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/drivers/usb/dwc2/gadget.c b/drivers/usb/dwc2/gadget.c
index 0abf73c..df43ec0 100644
--- a/drivers/usb/dwc2/gadget.c
+++ b/drivers/usb/dwc2/gadget.c
@@ -2606,7 +2606,9 @@ irq_retry:
for (idx = 1; idx < hsotg->num_of_eps; idx++) {
hs_ep = hsotg->eps_in[idx];

- if (!hs_ep->isochronous || hs_ep->has_correct_parity)
+ if (!hs_ep ||
+ !hs_ep->isochronous ||
+ hs_ep->has_correct_parity)
continue;

epctl_reg = DIEPCTL(idx);
@@ -2623,7 +2625,9 @@ irq_retry:
for (idx = 1; idx < hsotg->num_of_eps; idx++) {
hs_ep = hsotg->eps_out[idx];

- if (!hs_ep->isochronous || hs_ep->has_correct_parity)
+ if (!hs_ep ||
+ !hs_ep->isochronous ||
+ hs_ep->has_correct_parity)
continue;

epctl_reg = DOEPCTL(idx);
--
2.7.0.226.gfe986fe


2016-03-30 13:22:56

by Felipe Balbi

[permalink] [raw]
Subject: Re: [PATCH] usb: dwc2: gadget: avoid null dereference on incomplete transfer


Hi,

John Keeping <[email protected]> writes:
> Setting up a gadget with the uac2 function results in:
>
> Unable to handle kernel NULL pointer dereference at virtual address 00000058
> ...
> PC is at dwc2_hsotg_irq+0x7f0/0x908
> LR is at dwc2_hsotg_irq+0x4c/0x908
> Backtrace:
> [<c03cd5fc>] (dwc2_hsotg_irq) from [<c00814fc>] (handle_irq_event_percpu+0x130/0x3ec)
> [<c00813cc>] (handle_irq_event_percpu) from [<c0081800>] (handle_irq_event+0x48/0x6c)
>
> In all other loops we already skip endpoints that are null, so do so
> here as well.
>
> Signed-off-by: John Keeping <[email protected]>
> ---
> drivers/usb/dwc2/gadget.c | 8 ++++++--
> 1 file changed, 6 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/usb/dwc2/gadget.c b/drivers/usb/dwc2/gadget.c
> index 0abf73c..df43ec0 100644
> --- a/drivers/usb/dwc2/gadget.c
> +++ b/drivers/usb/dwc2/gadget.c
> @@ -2606,7 +2606,9 @@ irq_retry:
> for (idx = 1; idx < hsotg->num_of_eps; idx++) {
> hs_ep = hsotg->eps_in[idx];
>
> - if (!hs_ep->isochronous || hs_ep->has_correct_parity)
> + if (!hs_ep ||
> + !hs_ep->isochronous ||
> + hs_ep->has_correct_parity)

this is fine (even though choice of where to break line is a bit odd),
but I have a question about how the rest of the code works (a bit
off-topic, sorry)

> continue;
>
> epctl_reg = DIEPCTL(idx);

So, this means that the first ISO endpoint without correct parity will
be used. Isn't this a bit fragile ? What happens when you use a device
with several different interfaces using several different endpoints ?

Isn't there a register where we can check which physical endpoint
generated the IRQ ? Seems like you really wanna check what:

#define DIEPINT(_a) HSOTG_REG(0x908 + ((_a) * 0x20))

say about eps_in[idx].

> @@ -2623,7 +2625,9 @@ irq_retry:
> for (idx = 1; idx < hsotg->num_of_eps; idx++) {
> hs_ep = hsotg->eps_out[idx];
>
> - if (!hs_ep->isochronous || hs_ep->has_correct_parity)
> + if (!hs_ep ||
> + !hs_ep->isochronous ||
> + hs_ep->has_correct_parity)
> continue;
>
> epctl_reg = DOEPCTL(idx);

ditto for eps_out[idx] and:

#define DOEPINT(_a) HSOTG_REG(0xB08 + ((_a) * 0x20))

comments ?

--
balbi


Attachments:
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2016-03-30 22:45:31

by John Youn

[permalink] [raw]
Subject: Re: [PATCH] usb: dwc2: gadget: avoid null dereference on incomplete transfer

On 3/30/2016 6:22 AM, Felipe Balbi wrote:
>
> Hi,
>
> John Keeping <[email protected]> writes:
>> Setting up a gadget with the uac2 function results in:
>>
>> Unable to handle kernel NULL pointer dereference at virtual address 00000058
>> ...
>> PC is at dwc2_hsotg_irq+0x7f0/0x908
>> LR is at dwc2_hsotg_irq+0x4c/0x908
>> Backtrace:
>> [<c03cd5fc>] (dwc2_hsotg_irq) from [<c00814fc>] (handle_irq_event_percpu+0x130/0x3ec)
>> [<c00813cc>] (handle_irq_event_percpu) from [<c0081800>] (handle_irq_event+0x48/0x6c)
>>
>> In all other loops we already skip endpoints that are null, so do so
>> here as well.
>>
>> Signed-off-by: John Keeping <[email protected]>
>> ---
>> drivers/usb/dwc2/gadget.c | 8 ++++++--
>> 1 file changed, 6 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/usb/dwc2/gadget.c b/drivers/usb/dwc2/gadget.c
>> index 0abf73c..df43ec0 100644
>> --- a/drivers/usb/dwc2/gadget.c
>> +++ b/drivers/usb/dwc2/gadget.c
>> @@ -2606,7 +2606,9 @@ irq_retry:
>> for (idx = 1; idx < hsotg->num_of_eps; idx++) {
>> hs_ep = hsotg->eps_in[idx];
>>
>> - if (!hs_ep->isochronous || hs_ep->has_correct_parity)
>> + if (!hs_ep ||
>> + !hs_ep->isochronous ||
>> + hs_ep->has_correct_parity)
>
> this is fine (even though choice of where to break line is a bit odd),
> but I have a question about how the rest of the code works (a bit
> off-topic, sorry)
>
>> continue;
>>
>> epctl_reg = DIEPCTL(idx);
>
> So, this means that the first ISO endpoint without correct parity will
> be used. Isn't this a bit fragile ? What happens when you use a device
> with several different interfaces using several different endpoints ?
>
> Isn't there a register where we can check which physical endpoint
> generated the IRQ ? Seems like you really wanna check what:
>

We discussed this back when the patch was first submitted and
determined it should work fine like this. I don't remember exactly why
though.

But this ISOC parity stuff is a workaround and we have a series of
patches to correctly set up ISOC allowing us to remove it. We're doing
some final tests before we send them.

Regards,
John

2016-04-04 10:53:30

by Felipe Balbi

[permalink] [raw]
Subject: Re: [PATCH] usb: dwc2: gadget: avoid null dereference on incomplete transfer


Hi,

John Youn <[email protected]> writes:
> On 3/30/2016 6:22 AM, Felipe Balbi wrote:
>>
>> Hi,
>>
>> John Keeping <[email protected]> writes:
>>> Setting up a gadget with the uac2 function results in:
>>>
>>> Unable to handle kernel NULL pointer dereference at virtual address 00000058
>>> ...
>>> PC is at dwc2_hsotg_irq+0x7f0/0x908
>>> LR is at dwc2_hsotg_irq+0x4c/0x908
>>> Backtrace:
>>> [<c03cd5fc>] (dwc2_hsotg_irq) from [<c00814fc>] (handle_irq_event_percpu+0x130/0x3ec)
>>> [<c00813cc>] (handle_irq_event_percpu) from [<c0081800>] (handle_irq_event+0x48/0x6c)
>>>
>>> In all other loops we already skip endpoints that are null, so do so
>>> here as well.
>>>
>>> Signed-off-by: John Keeping <[email protected]>
>>> ---
>>> drivers/usb/dwc2/gadget.c | 8 ++++++--
>>> 1 file changed, 6 insertions(+), 2 deletions(-)
>>>
>>> diff --git a/drivers/usb/dwc2/gadget.c b/drivers/usb/dwc2/gadget.c
>>> index 0abf73c..df43ec0 100644
>>> --- a/drivers/usb/dwc2/gadget.c
>>> +++ b/drivers/usb/dwc2/gadget.c
>>> @@ -2606,7 +2606,9 @@ irq_retry:
>>> for (idx = 1; idx < hsotg->num_of_eps; idx++) {
>>> hs_ep = hsotg->eps_in[idx];
>>>
>>> - if (!hs_ep->isochronous || hs_ep->has_correct_parity)
>>> + if (!hs_ep ||
>>> + !hs_ep->isochronous ||
>>> + hs_ep->has_correct_parity)
>>
>> this is fine (even though choice of where to break line is a bit odd),
>> but I have a question about how the rest of the code works (a bit
>> off-topic, sorry)
>>
>>> continue;
>>>
>>> epctl_reg = DIEPCTL(idx);
>>
>> So, this means that the first ISO endpoint without correct parity will
>> be used. Isn't this a bit fragile ? What happens when you use a device
>> with several different interfaces using several different endpoints ?
>>
>> Isn't there a register where we can check which physical endpoint
>> generated the IRQ ? Seems like you really wanna check what:
>>
>
> We discussed this back when the patch was first submitted and
> determined it should work fine like this. I don't remember exactly why
> though.
>
> But this ISOC parity stuff is a workaround and we have a series of
> patches to correctly set up ISOC allowing us to remove it. We're doing
> some final tests before we send them.

fair enough, thanks

--
balbi


Attachments:
signature.asc (818.00 B)