[PATCH] usbip: Fix free of unallocated memory in vhci tx

[PATCH] usbip: Fix free of unallocated memory in vhci tx

[Suwan Kim]

iso_buffer should be set to NULL after use and free in the while loop.
In the case of isochronous URB in the while loop, iso_buffer is
allocated and after sending it to server, buffer is deallocated. And
then, if the next URB in the while loop is not a isochronous pipe,
iso_buffer still holds the previously deallocated buffer address and
kfree tries to free wrong buffer address.

Fixes: ea44d190764b (“usbip: Implement SG support to vhci-hcd and stub driver”)
Reported-by: kbuild test robot <lkp@intel.com>
Reported-by: Julia Lawall <julia.lawall@lip6.fr>
Signed-off-by: Suwan Kim <suwan.kim027@gmail.com>
---
 drivers/usb/usbip/vhci_tx.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/usb/usbip/vhci_tx.c b/drivers/usb/usbip/vhci_tx.c
index c3803785f6ef..b290e810d11b 100644
--- a/drivers/usb/usbip/vhci_tx.c
+++ b/drivers/usb/usbip/vhci_tx.c
@@ -73,6 +73,7 @@ static int vhci_send_cmd_submit(struct vhci_device *vdev)
 		memset(&pdu_header, 0, sizeof(pdu_header));
 		memset(&msg, 0, sizeof(msg));
 		memset(&iov, 0, sizeof(iov));
+		iso_buffer = NULL;
 
 		usbip_dbg_vhci_tx("setup txdata urb seqnum %lu\n",
 				  priv->seqnum);
-- 
2.21.0

Re: [PATCH] usbip: Fix free of unallocated memory in vhci tx

[Julia Lawall]

[-- Attachment #1: Type: text/plain, Size: 1545 bytes --]



On Mon, 21 Oct 2019, Suwan Kim wrote:

> iso_buffer should be set to NULL after use and free in the while loop.
> In the case of isochronous URB in the while loop, iso_buffer is
> allocated and after sending it to server, buffer is deallocated. And
> then, if the next URB in the while loop is not a isochronous pipe,
> iso_buffer still holds the previously deallocated buffer address and
> kfree tries to free wrong buffer address.
>
> Fixes: ea44d190764b (“usbip: Implement SG support to vhci-hcd and stub driver”)
> Reported-by: kbuild test robot <lkp@intel.com>
> Reported-by: Julia Lawall <julia.lawall@lip6.fr>
> Signed-off-by: Suwan Kim <suwan.kim027@gmail.com>
> ---
>  drivers/usb/usbip/vhci_tx.c | 1 +
>  1 file changed, 1 insertion(+)
>
> diff --git a/drivers/usb/usbip/vhci_tx.c b/drivers/usb/usbip/vhci_tx.c
> index c3803785f6ef..b290e810d11b 100644
> --- a/drivers/usb/usbip/vhci_tx.c
> +++ b/drivers/usb/usbip/vhci_tx.c
> @@ -73,6 +73,7 @@ static int vhci_send_cmd_submit(struct vhci_device *vdev)
>  		memset(&pdu_header, 0, sizeof(pdu_header));
>  		memset(&msg, 0, sizeof(msg));
>  		memset(&iov, 0, sizeof(iov));
> +		iso_buffer = NULL;

Somehow I would have put it after the kfree, since the kfree makes the
value invalid.  iso_buffer is already initialized to NULL for the first
iteration.  If you want to put the setting to NULL at the top of the loop,
maybe the = NULL in the first line should be removed.

julia

>
>  		usbip_dbg_vhci_tx("setup txdata urb seqnum %lu\n",
>  				  priv->seqnum);
> --
> 2.21.0
>
>

Re: [PATCH] usbip: Fix free of unallocated memory in vhci tx

[shuah]

On 10/21/19 9:08 AM, Julia Lawall wrote:
> 
> 
> On Mon, 21 Oct 2019, Suwan Kim wrote:
> 
>> iso_buffer should be set to NULL after use and free in the while loop.
>> In the case of isochronous URB in the while loop, iso_buffer is
>> allocated and after sending it to server, buffer is deallocated. And
>> then, if the next URB in the while loop is not a isochronous pipe,
>> iso_buffer still holds the previously deallocated buffer address and
>> kfree tries to free wrong buffer address.
>>
>> Fixes: ea44d190764b (“usbip: Implement SG support to vhci-hcd and stub driver”)
>> Reported-by: kbuild test robot <lkp@intel.com>
>> Reported-by: Julia Lawall <julia.lawall@lip6.fr>
>> Signed-off-by: Suwan Kim <suwan.kim027@gmail.com>
>> ---
>>   drivers/usb/usbip/vhci_tx.c | 1 +
>>   1 file changed, 1 insertion(+)
>>
>> diff --git a/drivers/usb/usbip/vhci_tx.c b/drivers/usb/usbip/vhci_tx.c
>> index c3803785f6ef..b290e810d11b 100644
>> --- a/drivers/usb/usbip/vhci_tx.c
>> +++ b/drivers/usb/usbip/vhci_tx.c
>> @@ -73,6 +73,7 @@ static int vhci_send_cmd_submit(struct vhci_device *vdev)
>>   		memset(&pdu_header, 0, sizeof(pdu_header));
>>   		memset(&msg, 0, sizeof(msg));
>>   		memset(&iov, 0, sizeof(iov));
>> +		iso_buffer = NULL;
> 
> Somehow I would have put it after the kfree, since the kfree makes the
> value invalid.  iso_buffer is already initialized to NULL for the first
> iteration.  If you want to put the setting to NULL at the top of the loop,
> maybe the = NULL in the first line should be removed.
> 

It makes sense to clear it after kfree() on line 150.

This kfree() and clearing iso_buffer are necessary only for
PIPE_ISOCHRONOUS case.

Please add a comment above that this is for isoc case.

thanks,
-- Shuah

Re: [PATCH] usbip: Fix free of unallocated memory in vhci tx

[Suwan Kim]

On Mon, Oct 21, 2019 at 01:28:54PM -0600, shuah wrote:
> On 10/21/19 9:08 AM, Julia Lawall wrote:
> > 
> > 
> > On Mon, 21 Oct 2019, Suwan Kim wrote:
> > 
> > > iso_buffer should be set to NULL after use and free in the while loop.
> > > In the case of isochronous URB in the while loop, iso_buffer is
> > > allocated and after sending it to server, buffer is deallocated. And
> > > then, if the next URB in the while loop is not a isochronous pipe,
> > > iso_buffer still holds the previously deallocated buffer address and
> > > kfree tries to free wrong buffer address.
> > > 
> > > Fixes: ea44d190764b (“usbip: Implement SG support to vhci-hcd and stub driver”)
> > > Reported-by: kbuild test robot <lkp@intel.com>
> > > Reported-by: Julia Lawall <julia.lawall@lip6.fr>
> > > Signed-off-by: Suwan Kim <suwan.kim027@gmail.com>
> > > ---
> > >   drivers/usb/usbip/vhci_tx.c | 1 +
> > >   1 file changed, 1 insertion(+)
> > > 
> > > diff --git a/drivers/usb/usbip/vhci_tx.c b/drivers/usb/usbip/vhci_tx.c
> > > index c3803785f6ef..b290e810d11b 100644
> > > --- a/drivers/usb/usbip/vhci_tx.c
> > > +++ b/drivers/usb/usbip/vhci_tx.c
> > > @@ -73,6 +73,7 @@ static int vhci_send_cmd_submit(struct vhci_device *vdev)
> > >   		memset(&pdu_header, 0, sizeof(pdu_header));
> > >   		memset(&msg, 0, sizeof(msg));
> > >   		memset(&iov, 0, sizeof(iov));
> > > +		iso_buffer = NULL;
> > 
> > Somehow I would have put it after the kfree, since the kfree makes the
> > value invalid.  iso_buffer is already initialized to NULL for the first
> > iteration.  If you want to put the setting to NULL at the top of the loop,
> > maybe the = NULL in the first line should be removed.
> > 
> 
> It makes sense to clear it after kfree() on line 150.
> 
> This kfree() and clearing iso_buffer are necessary only for
> PIPE_ISOCHRONOUS case.
> 
> Please add a comment above that this is for isoc case.

Ok. I will send v2.

Regards
Suwan Kim