[PATCH] Bluetooth: Fix for double free of st buffer.

[PATCH] Bluetooth: Fix for double free of st buffer.

[ramm]

From: Ram Malovany <ramm@ti.com>

When the Shared Transport line discipline driver (st_core) get data it
pushes the skb received to the relevant protocol stacks , it then
excepts that the relevant protocol stacks should handle the buffer ,
and if it cannot then the stack should respond with an error.
In our case the Bluetooth driver for shared transport (btwilink) should
always be able to handle the buffer , in case of an error it will
release it , thus we always should return 0.

Signed-off-by: Ram Malovany <ramm@ti.com>
---
 drivers/bluetooth/btwilink.c |   12 ++++++++----
 1 files changed, 8 insertions(+), 4 deletions(-)

diff --git a/drivers/bluetooth/btwilink.c b/drivers/bluetooth/btwilink.c
index 8869469..1f60d84 100644
--- a/drivers/bluetooth/btwilink.c
+++ b/drivers/bluetooth/btwilink.c
@@ -94,18 +94,22 @@ static void st_reg_completion_cb(void *priv_data, char data)
 }
 
 /* Called by Shared Transport layer when receive data is
- * available */
+ * available
+ * Return:
+ * 0 if buffer handled (affectivly allways even if error found)
+ * if return !=0 the buffer will be freed by the st
+ */
 static long st_receive(void *priv_data, struct sk_buff *skb)
 {
 	struct ti_st *lhst = priv_data;
 	int err;
 
 	if (!skb)
-		return -EFAULT;
+		return 0;
 
 	if (!lhst) {
 		kfree_skb(skb);
-		return -EFAULT;
+		return 0;
 	}
 
 	skb->dev = (void *) lhst->hdev;
@@ -114,7 +118,7 @@ static long st_receive(void *priv_data, struct sk_buff *skb)
 	err = hci_recv_frame(skb);
 	if (err < 0) {
 		BT_ERR("Unable to push skb to HCI core(%d)", err);
-		return err;
+		return 0;
 	}
 
 	lhst->hdev->stat.byte_rx += skb->len;
-- 
1.7.4.1

Re: [PATCH] Bluetooth: Fix for double free of st buffer.

[Gustavo Padovan]

Hi Ram,

* ramm@ti.com <ramm@ti.com> [2012-07-17 10:49:30 +0300]:

> From: Ram Malovany <ramm@ti.com>
> 
> When the Shared Transport line discipline driver (st_core) get data it
> pushes the skb received to the relevant protocol stacks , it then
> excepts that the relevant protocol stacks should handle the buffer ,
> and if it cannot then the stack should respond with an error.
> In our case the Bluetooth driver for shared transport (btwilink) should
> always be able to handle the buffer , in case of an error it will
> release it , thus we always should return 0.
> 
> Signed-off-by: Ram Malovany <ramm@ti.com>
> ---
>  drivers/bluetooth/btwilink.c |   12 ++++++++----
>  1 files changed, 8 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/bluetooth/btwilink.c b/drivers/bluetooth/btwilink.c
> index 8869469..1f60d84 100644
> --- a/drivers/bluetooth/btwilink.c
> +++ b/drivers/bluetooth/btwilink.c
> @@ -94,18 +94,22 @@ static void st_reg_completion_cb(void *priv_data, char data)
>  }
>  
>  /* Called by Shared Transport layer when receive data is
> - * available */
> + * available
> + * Return:
> + * 0 if buffer handled (affectivly allways even if error found)
> + * if return !=0 the buffer will be freed by the st
> + */
>  static long st_receive(void *priv_data, struct sk_buff *skb)
>  {
>  	struct ti_st *lhst = priv_data;
>  	int err;
>  
>  	if (!skb)
> -		return -EFAULT;
> +		return 0;
>  
>  	if (!lhst) {
>  		kfree_skb(skb);

If you remove this call to kfree_skb() from here doesn't it fixes your
problem?

	Gustavo

RE: [PATCH] Bluetooth: Fix for double free of st buffer.

[Malovany, Ram]

HI Gustavo,

> -----Original Message-----
> From: Gustavo Padovan [mailto:gustavo@padovan.org]
> Sent: Wednesday, July 25, 2012 2:01 AM
> To: Malovany, Ram
> Cc: linux-bluetooth@vger.kernel.org
> Subject: Re: [PATCH] Bluetooth: Fix for double free of st buffer.
> 
> Hi Ram,
> 
> * ramm@ti.com <ramm@ti.com> [2012-07-17 10:49:30 +0300]:
> 
> > From: Ram Malovany <ramm@ti.com>
> >
> > When the Shared Transport line discipline driver (st_core) get data it
> > pushes the skb received to the relevant protocol stacks , it then
> > excepts that the relevant protocol stacks should handle the buffer ,
> > and if it cannot then the stack should respond with an error.
> > In our case the Bluetooth driver for shared transport (btwilink) should
> > always be able to handle the buffer , in case of an error it will
> > release it , thus we always should return 0.
> >
> > Signed-off-by: Ram Malovany <ramm@ti.com>
> > ---
> >  drivers/bluetooth/btwilink.c |   12 ++++++++----
> >  1 files changed, 8 insertions(+), 4 deletions(-)
> >
> > diff --git a/drivers/bluetooth/btwilink.c b/drivers/bluetooth/btwilink.c
> > index 8869469..1f60d84 100644
> > --- a/drivers/bluetooth/btwilink.c
> > +++ b/drivers/bluetooth/btwilink.c
> > @@ -94,18 +94,22 @@ static void st_reg_completion_cb(void *priv_data, char
> data)
> >  }
> >
> >  /* Called by Shared Transport layer when receive data is
> > - * available */
> > + * available
> > + * Return:
> > + * 0 if buffer handled (affectivly allways even if error found)
> > + * if return !=0 the buffer will be freed by the st
> > + */
> >  static long st_receive(void *priv_data, struct sk_buff *skb)
> >  {
> >  	struct ti_st *lhst = priv_data;
> >  	int err;
> >
> >  	if (!skb)
> > -		return -EFAULT;
> > +		return 0;
> >
> >  	if (!lhst) {
> >  		kfree_skb(skb);
> 
> If you remove this call to kfree_skb() from here doesn't it fixes your
> problem?
> 
> 	Gustavo

You are correct , I was going to send a new version for this patch.

Thanks,
Ram

RE: [PATCH] Bluetooth: Fix for double free of st buffer.

[Malovany, Ram]

HI Gustavo,

> -----Original Message-----
> From: Malovany, Ram
> Sent: Wednesday, July 25, 2012 11:01 AM
> To: 'Gustavo Padovan'
> Cc: linux-bluetooth@vger.kernel.org
> Subject: RE: [PATCH] Bluetooth: Fix for double free of st buffer.
> 
> HI Gustavo,
> 
> > -----Original Message-----
> > From: Gustavo Padovan [mailto:gustavo@padovan.org]
> > Sent: Wednesday, July 25, 2012 2:01 AM
> > To: Malovany, Ram
> > Cc: linux-bluetooth@vger.kernel.org
> > Subject: Re: [PATCH] Bluetooth: Fix for double free of st buffer.
> >
> > Hi Ram,
> >
> > * ramm@ti.com <ramm@ti.com> [2012-07-17 10:49:30 +0300]:
> >
> > > From: Ram Malovany <ramm@ti.com>
> > >
> > > When the Shared Transport line discipline driver (st_core) get data it
> > > pushes the skb received to the relevant protocol stacks , it then
> > > excepts that the relevant protocol stacks should handle the buffer ,
> > > and if it cannot then the stack should respond with an error.
> > > In our case the Bluetooth driver for shared transport (btwilink) should
> > > always be able to handle the buffer , in case of an error it will
> > > release it , thus we always should return 0.
> > >
> > > Signed-off-by: Ram Malovany <ramm@ti.com>
> > > ---
> > >  drivers/bluetooth/btwilink.c |   12 ++++++++----
> > >  1 files changed, 8 insertions(+), 4 deletions(-)
> > >
> > > diff --git a/drivers/bluetooth/btwilink.c b/drivers/bluetooth/btwilink.c
> > > index 8869469..1f60d84 100644
> > > --- a/drivers/bluetooth/btwilink.c
> > > +++ b/drivers/bluetooth/btwilink.c
> > > @@ -94,18 +94,22 @@ static void st_reg_completion_cb(void *priv_data, char
> > data)
> > >  }
> > >
> > >  /* Called by Shared Transport layer when receive data is
> > > - * available */
> > > + * available
> > > + * Return:
> > > + * 0 if buffer handled (affectivly allways even if error found)
> > > + * if return !=0 the buffer will be freed by the st
> > > + */
> > >  static long st_receive(void *priv_data, struct sk_buff *skb)
> > >  {
> > >  	struct ti_st *lhst = priv_data;
> > >  	int err;
> > >
> > >  	if (!skb)
> > > -		return -EFAULT;
> > > +		return 0;
> > >
> > >  	if (!lhst) {
> > >  		kfree_skb(skb);
> >
> > If you remove this call to kfree_skb() from here doesn't it fixes your
> > problem?
> >
> > 	Gustavo

I looked at the fix again , and I think we shouldn't change it since the main problem that I am observing her is not the kfree_skb() at this point ,
The problem is related to who is in charge of the buffer at this point , and in our case the function hci_recv_frame() can use different 
transports and upon an error it will free the buffer as well , in my fix I made sure that st_receive() will always take care of the buffer.
> 
> You are correct , I was going to send a new version for this patch.
> 
> Thanks,
> Ram

RE: [PATCH] Bluetooth: Fix for double free of st buffer.

[Malovany, Ram]

Ping 

> -----Original Message-----
> From: Malovany, Ram
> Sent: Wednesday, July 25, 2012 11:31 AM
> To: 'Gustavo Padovan'
> Cc: 'linux-bluetooth@vger.kernel.org'
> Subject: RE: [PATCH] Bluetooth: Fix for double free of st buffer.
> 
> HI Gustavo,
> 
> > -----Original Message-----
> > From: Malovany, Ram
> > Sent: Wednesday, July 25, 2012 11:01 AM
> > To: 'Gustavo Padovan'
> > Cc: linux-bluetooth@vger.kernel.org
> > Subject: RE: [PATCH] Bluetooth: Fix for double free of st buffer.
> >
> > HI Gustavo,
> >
> > > -----Original Message-----
> > > From: Gustavo Padovan [mailto:gustavo@padovan.org]
> > > Sent: Wednesday, July 25, 2012 2:01 AM
> > > To: Malovany, Ram
> > > Cc: linux-bluetooth@vger.kernel.org
> > > Subject: Re: [PATCH] Bluetooth: Fix for double free of st buffer.
> > >
> > > Hi Ram,
> > >
> > > * ramm@ti.com <ramm@ti.com> [2012-07-17 10:49:30 +0300]:
> > >
> > > > From: Ram Malovany <ramm@ti.com>
> > > >
> > > > When the Shared Transport line discipline driver (st_core) get
> > > > data it pushes the skb received to the relevant protocol stacks ,
> > > > it then excepts that the relevant protocol stacks should handle
> > > > the buffer , and if it cannot then the stack should respond with an
> error.
> > > > In our case the Bluetooth driver for shared transport (btwilink)
> > > > should always be able to handle the buffer , in case of an error
> > > > it will release it , thus we always should return 0.
> > > >
> > > > Signed-off-by: Ram Malovany <ramm@ti.com>
> > > > ---
> > > >  drivers/bluetooth/btwilink.c |   12 ++++++++----
> > > >  1 files changed, 8 insertions(+), 4 deletions(-)
> > > >
> > > > diff --git a/drivers/bluetooth/btwilink.c
> > > > b/drivers/bluetooth/btwilink.c index 8869469..1f60d84 100644
> > > > --- a/drivers/bluetooth/btwilink.c
> > > > +++ b/drivers/bluetooth/btwilink.c
> > > > @@ -94,18 +94,22 @@ static void st_reg_completion_cb(void
> > > > *priv_data, char
> > > data)
> > > >  }
> > > >
> > > >  /* Called by Shared Transport layer when receive data is
> > > > - * available */
> > > > + * available
> > > > + * Return:
> > > > + * 0 if buffer handled (affectivly allways even if error found)
> > > > + * if return !=0 the buffer will be freed by the st */
> > > >  static long st_receive(void *priv_data, struct sk_buff *skb)  {
> > > >  	struct ti_st *lhst = priv_data;
> > > >  	int err;
> > > >
> > > >  	if (!skb)
> > > > -		return -EFAULT;
> > > > +		return 0;
> > > >
> > > >  	if (!lhst) {
> > > >  		kfree_skb(skb);
> > >
> > > If you remove this call to kfree_skb() from here doesn't it fixes
> > > your problem?
> > >
> > > 	Gustavo
> 
> I looked at the fix again , and I think we shouldn't change it since the main
> problem that I am observing her is not the kfree_skb() at this point , The
> problem is related to who is in charge of the buffer at this point , and in
> our case the function hci_recv_frame() can use different transports and upon
> an error it will free the buffer as well , in my fix I made sure that
> st_receive() will always take care of the buffer.
> >
> > You are correct , I was going to send a new version for this patch.
> >
> > Thanks,
> > Ram