On Sun, Oct 17, 2010 at 17:34 +0200, Jiri Slaby wrote:
> On 10/17/2010 04:41 PM, Vasiliy Kulikov wrote:
> > Structure new_line is copied to userland with some padding fields unitialized.
> > It leads to leaking of stack memory.
>
> I think your tool has a bug. I must admit I fail to see the padding
> which would cause leaks. Could you elaborate?
I didn't use any tool except "grep copy_to_user" :)
typedef struct {
unsigned int clock_rate; /* bits per second */
unsigned int clock_type; /* internal, external, TX-internal etc. */
unsigned short loopback;
} sync_serial_settings; /* V.35, V.24, X.21 */
On x86_64 sizeof(sync_serial_settings) = 4 + 4 + 2 + 2 = 12.
The last 2 is padding.
>
> > Signed-off-by: Vasiliy Kulikov <segooon@xxxxxxxxx>
> > ---
> > Compile tested.
> >
> > drivers/char/synclink.c | 2 ++
> > 1 files changed, 2 insertions(+), 0 deletions(-)
> >
> > diff --git a/drivers/char/synclink.c b/drivers/char/synclink.c
> > index 3a6824f..abd0867 100644
> > --- a/drivers/char/synclink.c
> > +++ b/drivers/char/synclink.c
> > @@ -7846,6 +7846,8 @@ static int hdlcdev_ioctl(struct net_device *dev, struct ifreq *ifr, int cmd)
> > if (cmd != SIOCWANDEV)
> > return hdlc_ioctl(dev, ifr, cmd);
> >
> > + memset(&new_line, 0, size);
> > +
> > switch(ifr->ifr_settings.type) {
> > case IF_GET_IFACE: /* return current sync_serial_settings */
> >
>
>
> --
> js
> suse labs
--
Vasiliy
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