Re: [PATCH] staging: rtl8192e: Fix possible buffer overflow in _rtl92e_wx_set_scan

Dan Carpenter
2021-02-26T12:31:35Z

On Fri, Feb 26, 2021 at 01:06:46PM +0100, Greg KH wrote:
> On Fri, Feb 26, 2021 at 11:48:29AM +0000, Lee Gibson wrote:
> > Function _rtl92e_wx_set_scan calls memcpy without checking the length.
> > A user could control that length and trigger a buffer overflow.
> > Fix by checking the length is within the maximum allowed size.
> >
> > Signed-off-by: Lee Gibson <leegib@gmail.com>
> > ---
> > drivers/staging/rtl8192e/rtl8192e/rtl_wx.c | 3 +++
> > 1 file changed, 3 insertions(+)
> >
> > diff --git a/drivers/staging/rtl8192e/rtl8192e/rtl_wx.c b/drivers/staging/rtl8192e/rtl8192e/rtl_wx.c
> > index 16bcee13f64b..2acc4f314732 100644
> > --- a/drivers/staging/rtl8192e/rtl8192e/rtl_wx.c
> > +++ b/drivers/staging/rtl8192e/rtl8192e/rtl_wx.c
> > @@ -406,6 +406,9 @@ static int _rtl92e_wx_set_scan(struct net_device *dev,
> > struct iw_scan_req *req = (struct iw_scan_req *)b;
> >
> > if (req->essid_len) {
> > + if (req->essid_len > IW_ESSID_MAX_SIZE)
> > + req->essid_len = IW_ESSID_MAX_SIZE;
> > +
>
> How about using the "pattern" the other wireless drivers use of:
>
> int len = min((int)req->essid_len, IW_ESSID_MAX_SIZE);

I bet checkpatch complains that we should use min_t() instead (but I'm
too lazy to verify).

int len = min_t(int, req->essid_len, IW_ESSID_MAX_SIZE);