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| author | Johan Hovold <johan@kernel.org> | 2021-10-25 13:45:30 +0200 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2021-10-26 19:10:18 +0200 |
| commit | a23461c47482fc232ffc9b819539d1f837adf2b1 (patch) | |
| tree | ee14b20eff1fad44d75cecc8ca64bf2c73de1fe2 /drivers/comedi | |
| parent | 16b0314aa746be6c84c0bc6eca9dde0dce2e99df (diff) | |
| download | lwn-a23461c47482fc232ffc9b819539d1f837adf2b1.tar.gz lwn-a23461c47482fc232ffc9b819539d1f837adf2b1.zip | |
comedi: vmk80xx: fix transfer-buffer overflows
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>
Diffstat (limited to 'drivers/comedi')
| -rw-r--r-- | drivers/comedi/drivers/vmk80xx.c | 6 |
1 files 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; |