| From a23461c47482fc232ffc9b819539d1f837adf2b1 Mon Sep 17 00:00:00 2001 |
| From: Johan Hovold <johan@kernel.org> |
| Date: Mon, 25 Oct 2021 13:45:30 +0200 |
| Subject: comedi: vmk80xx: fix transfer-buffer overflows |
| |
| From: Johan Hovold <johan@kernel.org> |
| |
| commit a23461c47482fc232ffc9b819539d1f837adf2b1 upstream. |
| |
| 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> |
| Reviewed-by: Ian Abbott <abbotti@mev.co.uk> |
| Link: https://lore.kernel.org/r/20211025114532.4599-4-johan@kernel.org |
| Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| --- |
| drivers/comedi/drivers/vmk80xx.c | 6 ++++-- |
| 1 file changed, 4 insertions(+), 2 deletions(-) |
| |
| --- 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(str |
| 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; |