From: Johan Hovold <johan@kernel.org> stable inclusion from stable-v4.19.217 commit 7a2021b896de1ad559d33b5c5cdd20b982242088 category: bugfix bugzilla: https://gitee.com/src-openeuler/kernel/issues/I9RD17 CVE: CVE-2021-47475 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=... -------------------------------- 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> Signed-off-by: Cai Xinchen <caixinchen1@huawei.com> --- drivers/staging/comedi/drivers/vmk80xx.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/drivers/staging/comedi/drivers/vmk80xx.c b/drivers/staging/comedi/drivers/vmk80xx.c index 656c6cdb29af..40a122e12610 100644 --- a/drivers/staging/comedi/drivers/vmk80xx.c +++ b/drivers/staging/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 @@ -664,12 +666,12 @@ 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; -- 2.34.1