Re: [PATCH] rtl8723bs/ioctl_linux: Add a security check to copy_from_user()

[Dan Carpenter]

On Sun, Dec 23, 2018 at 06:13:02PM -0600, Aditya Pakki wrote:
> diff --git a/drivers/staging/rtl8723bs/os_dep/ioctl_linux.c 
> b/drivers/staging/rtl8723bs/os_dep/ioctl_linux.c
> index b8631baf128d..9992caa8c839 100644
> --- a/drivers/staging/rtl8723bs/os_dep/ioctl_linux.c
> +++ b/drivers/staging/rtl8723bs/os_dep/ioctl_linux.c
> @@ -2577,14 +2577,19 @@ static int rtw_wps_start(struct net_device *dev,
>   struct adapter *padapter = (struct adapter *)rtw_netdev_priv(dev);
>   struct iw_point *pdata = >data;
>   u32   u32wps_start = 0;
> -unsigned int uintRet = 0;
>  
>   if ((true == padapter->bDriverStopped) ||(true 
> ==padapter->bSurpriseRemoved) || (NULL == pdata)) {
>   ret = -EINVAL;
>   goto exit;
>   }
>  
> - uintRet = copy_from_user((void*)_start, pdata->pointer, 4);
> + ret = copy_from_user((void *)_start, pdata->pointer, 4);
> +
> + if (ret) {
> + ret = -EINVAL;
> + goto exit;

Good eye for spotting this bug.  :)

Really this function is not useful though so we should just delete it.
All the CONFIG_INTEL_WIDI stuff is dead code.

Also if copy_from_user() the correct error code is -EFAULT.  And we
would normally write it like this:

if (copy_from_user((void *)_start, pdata->pointer, 4)) {
ret = -EFAULT;
goto exit;
}

But in this case, since this is dead code we should just delete
rtw_wps_start() and put a NULL in the rtw_private_handler[] array where
it used to be.

regards,
dan carpenter

[PATCH] rtl8723bs/ioctl_linux: Add a security check to copy_from_user()

[Aditya Pakki]

Currently, the return value of copy_from_user is not checked.
extra is assigned to u32wps_start irrespective of these failures.

Signed-off-by: Aditya Pakki 
---
 drivers/staging/rtl8723bs/os_dep/ioctl_linux.c | 9 +++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/drivers/staging/rtl8723bs/os_dep/ioctl_linux.c 
b/drivers/staging/rtl8723bs/os_dep/ioctl_linux.c
index b8631baf128d..9992caa8c839 100644
--- a/drivers/staging/rtl8723bs/os_dep/ioctl_linux.c
+++ b/drivers/staging/rtl8723bs/os_dep/ioctl_linux.c
@@ -2577,14 +2577,19 @@ static int rtw_wps_start(struct net_device *dev,
struct adapter *padapter = (struct adapter *)rtw_netdev_priv(dev);
struct iw_point *pdata = >data;
u32   u32wps_start = 0;
-unsigned int uintRet = 0;
 
if ((true == padapter->bDriverStopped) ||(true 
==padapter->bSurpriseRemoved) || (NULL == pdata)) {
ret = -EINVAL;
goto exit;
}
 
-   uintRet = copy_from_user((void*)_start, pdata->pointer, 4);
+   ret = copy_from_user((void *)_start, pdata->pointer, 4);
+
+   if (ret) {
+   ret = -EINVAL;
+   goto exit;
+   }
+
if (u32wps_start == 0)
u32wps_start = *extra;
 
-- 
2.17.1