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SubjectRe: [PATCH] Fix refcount leak in tty_port.c
On 07/12/2013 10:04 AM, Peter Hurley wrote:
> On 07/12/2013 06:30 AM, Gustavo Padovan wrote:
>> Hi Gianluca,
>>
>> * Gianluca Anzolin <gianluca@sottospazio.it> [2013-07-09 10:35:35 +0200]:
>>
>>> Hello,
>>>
>>> In linux 3.10 in the file drivers/tty/tty_port.c the function
>>> tty_port_tty_hangup may leak a tty reference:
>>>
>>> struct tty_struct *tty = tty_port_tty_get(port);
>>>
>>> if (tty && (!check_clocal || !C_CLOCAL(tty))) {
>>> tty_hangup(tty);
>>> tty_kref_put(tty);
>>> }
>>>
>>> If tty != NULL and the second condition is false we never call tty_kref_put and
>>> the reference is leaked.
>
> Good catch.
>
>>> Fix by nesting two if statements.
>>>
>>> Signed-off-by: Gianluca Anzolin <gianluca@sottospazio.it>
>>
>> As mentioned by Gianluca this is a regression of aa27a094 and we depend on
>> this patch to go ahead with some fixes in the bluetooth subsystem.
>
> Gustavo,
>
> There's no direct dependency; ie., there aren't merge issues here.
> We should progress with the fixes to rfcomm independent of this patch.
>
>> Gianluca, it might help if you send a proper git inline formated patch,
>> mentioning the issue and which regression you are fixing. It makes
>> maintainer's life easier.
>
> As Gustavo points out, please inline the patch otherwise commenters
> have to do it for you.

Gianluca,

I think Greg may be expecting you to address the comments from myself
and Gustavo before accepting this patch.

Greg, is that the case?

Regards,
Peter Hurley

>> Also add my Ack to the patch:
> >
>>
>> Acked-by: Gustavo Padovan <gustavo.padovan@collabora.co.uk>
>>
>> Gustavo
>
> Copy of the Gianluca's patch with my comments
>
> --- %< ---
>
> Please put a proper commit message here, including that this is
> a regression and the commit id that caused the regression so this patch
> can eventually make its way to stable.
>
>
> > diff --git a/drivers/tty/tty_port.c b/drivers/tty/tty_port.c
> > index 121aeb9..2198f7d 100644
> > --- a/drivers/tty/tty_port.c
> > +++ b/drivers/tty/tty_port.c
> > @@ -256,8 +256,9 @@ void tty_port_tty_hangup(struct tty_port *port, bool check_clocal)
> > {
> > struct tty_struct *tty = tty_port_tty_get(port);
> >
> > - if (tty && (!check_clocal || !C_CLOCAL(tty))) {
> > - tty_hangup(tty);
> > + if (tty) {
> > + if (!check_clocal || !C_CLOCAL(tty))
> > + tty_hangup(tty);
> > tty_kref_put(tty);
> > }
> > }
>
>
> tty_kref_put() already checks for NULL tty. I would prefer:
>
> {
> struct tty_struct *tty = tty_port_tty_get(port);
>
> if (tty && (!check_clocal || !C_CLOCAL(tty)))
> tty_hangup(tty);
> tty_kref_put(tty);
> }




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