[PATCH] Fix refcount leak in tty_port.c

[PATCH] Fix refcount leak in tty_port.c

[Gianluca Anzolin]

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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.

Fix by nesting two if statements.

Signed-off-by: Gianluca Anzolin <gianluca@sottospazio.it>

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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);
 	}
 }

Re: [PATCH] Fix refcount leak in tty_port.c

[Gustavo Padovan]

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.
> 
> 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.

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. Also add my Ack to the patch:

Acked-by: Gustavo Padovan <gustavo.padovan@collabora.co.uk>

	Gustavo

Re: [PATCH] Fix refcount leak in tty_port.c

[Peter Hurley]

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.

> 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);
}

Re: [PATCH] Fix refcount leak in tty_port.c

[Peter Hurley]

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);
> }

Re: [PATCH] Fix refcount leak in tty_port.c

[Greg KH]

On Wed, Jul 24, 2013 at 10:11:47AM -0400, Peter Hurley wrote:
> 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?

Yes, I thought a new version was coming, so I dropped this one.  Can
someone please fix this up and resend?

thanks,

greg k-h

Re: [PATCH] Fix refcount leak in tty_port.c

[Greg KH]

On Fri, Jul 12, 2013 at 11:47:33AM +0200, Gianluca Anzolin wrote:
> Hello,
> 
> I'm sorry to bother you again, I'm just pinging to see if you received the
> patch or if it got lost in the noise. It fixes a regression introduced in git
> commit aa27a094e2c2e
> 
> I have another patch for rfcomm tty waiting for this fix to get applied.

I have it, just waiting for 3.11-rc1 to come out before dealing with any
new patches.

thanks,

greg k-h

Re: [PATCH] Fix refcount leak in tty_port.c

[Gianluca Anzolin]

Hello,

I'm sorry to bother you again, I'm just pinging to see if you received the
patch or if it got lost in the noise. It fixes a regression introduced in git
commit aa27a094e2c2e

I have another patch for rfcomm tty waiting for this fix to get applied.

Thank you,

Gianluca

On Tue, Jul 09, 2013 at 10:35:35AM +0200, Gianluca Anzolin wrote:
> 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.
> 
> Fix by nesting two if statements.
> 
> Signed-off-by: Gianluca Anzolin <gianluca@sottospazio.it>

> 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);
>  	}
>  }