| Message ID | 20211025114532.4599-4-johan@kernel.org (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | comedi: misc fixes | expand |
On 25/10/2021 12:45, Johan Hovold wrote: > The driver uses endpoint-sized USB transfer buffers but up until > recently had no sanity checks on the sizes. > > Commit e1f13c879a7c ("staging: comedi: check validity of wMaxPacketSize > of usb endpoints found") inadvertently fixed NULL-pointer dereferences > when accessing the transfer buffers in case a malicious device has a > zero wMaxPacketSize. > > Make sure to allocate buffers large enough to handle also the other > accesses that are done without a size check (e.g. byte 18 in > vmk80xx_cnt_insn_read() for the VMK8061_MODEL) to avoid writing beyond > the buffers, for example, when doing descriptor fuzzing. > > The original driver was for a low-speed device with 8-byte buffers. > Support was later added for a device that uses bulk transfers and is > presumably a full-speed device with a maximum 64-byte wMaxPacketSize. > > Fixes: 985cafccbf9b ("Staging: Comedi: vmk80xx: Add k8061 support") > Cc: stable@vger.kernel.org # 2.6.31 > Signed-off-by: Johan Hovold <johan@kernel.org> > --- > drivers/comedi/drivers/vmk80xx.c | 6 ++++-- > 1 file changed, 4 insertions(+), 2 deletions(-) > > diff --git a/drivers/comedi/drivers/vmk80xx.c b/drivers/comedi/drivers/vmk80xx.c > index 9f920819cd74..f2c1572d0cd7 100644 > --- a/drivers/comedi/drivers/vmk80xx.c > +++ b/drivers/comedi/drivers/vmk80xx.c > @@ -90,6 +90,8 @@ enum { > #define IC3_VERSION BIT(0) > #define IC6_VERSION BIT(1) > > +#define MIN_BUF_SIZE 64 > + > enum vmk80xx_model { > VMK8055_MODEL, > VMK8061_MODEL > @@ -678,12 +680,12 @@ static int vmk80xx_alloc_usb_buffers(struct comedi_device *dev) > struct vmk80xx_private *devpriv = dev->private; > size_t size; > > - size = usb_endpoint_maxp(devpriv->ep_rx); > + size = max(usb_endpoint_maxp(devpriv->ep_rx), MIN_BUF_SIZE); > devpriv->usb_rx_buf = kzalloc(size, GFP_KERNEL); > if (!devpriv->usb_rx_buf) > return -ENOMEM; > > - size = usb_endpoint_maxp(devpriv->ep_tx); > + size = max(usb_endpoint_maxp(devpriv->ep_rx), MIN_BUF_SIZE); > devpriv->usb_tx_buf = kzalloc(size, GFP_KERNEL); > if (!devpriv->usb_tx_buf) > return -ENOMEM; > Looks good, thanks! Reviewed-by: Ian Abbott <abbotti@mev.co.uk>
diff --git a/drivers/comedi/drivers/vmk80xx.c b/drivers/comedi/drivers/vmk80xx.c index 9f920819cd74..f2c1572d0cd7 100644 --- a/drivers/comedi/drivers/vmk80xx.c +++ b/drivers/comedi/drivers/vmk80xx.c @@ -90,6 +90,8 @@ enum { #define IC3_VERSION BIT(0) #define IC6_VERSION BIT(1) +#define MIN_BUF_SIZE 64 + enum vmk80xx_model { VMK8055_MODEL, VMK8061_MODEL @@ -678,12 +680,12 @@ static int vmk80xx_alloc_usb_buffers(struct comedi_device *dev) struct vmk80xx_private *devpriv = dev->private; size_t size; - size = usb_endpoint_maxp(devpriv->ep_rx); + size = max(usb_endpoint_maxp(devpriv->ep_rx), MIN_BUF_SIZE); devpriv->usb_rx_buf = kzalloc(size, GFP_KERNEL); if (!devpriv->usb_rx_buf) return -ENOMEM; - size = usb_endpoint_maxp(devpriv->ep_tx); + size = max(usb_endpoint_maxp(devpriv->ep_rx), MIN_BUF_SIZE); devpriv->usb_tx_buf = kzalloc(size, GFP_KERNEL); if (!devpriv->usb_tx_buf) return -ENOMEM;
The driver uses endpoint-sized USB transfer buffers but up until recently had no sanity checks on the sizes. Commit e1f13c879a7c ("staging: comedi: check validity of wMaxPacketSize of usb endpoints found") inadvertently fixed NULL-pointer dereferences when accessing the transfer buffers in case a malicious device has a zero wMaxPacketSize. Make sure to allocate buffers large enough to handle also the other accesses that are done without a size check (e.g. byte 18 in vmk80xx_cnt_insn_read() for the VMK8061_MODEL) to avoid writing beyond the buffers, for example, when doing descriptor fuzzing. The original driver was for a low-speed device with 8-byte buffers. Support was later added for a device that uses bulk transfers and is presumably a full-speed device with a maximum 64-byte wMaxPacketSize. Fixes: 985cafccbf9b ("Staging: Comedi: vmk80xx: Add k8061 support") Cc: stable@vger.kernel.org # 2.6.31 Signed-off-by: Johan Hovold <johan@kernel.org> --- drivers/comedi/drivers/vmk80xx.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-)