flags field in ifreq is only 16 bit wide, but we read it as a 32 bit value. If userspace doesn't zero-initialize unused fields, this will lead to failures.
Signed-off-by: Michael S. Tsirkin <[email protected]> --- drivers/net/macvtap.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) diff --git a/drivers/net/macvtap.c b/drivers/net/macvtap.c index af90ab5..de88285 100644 --- a/drivers/net/macvtap.c +++ b/drivers/net/macvtap.c @@ -1011,7 +1011,7 @@ static long macvtap_ioctl(struct file *file, unsigned int cmd, void __user *argp = (void __user *)arg; struct ifreq __user *ifr = argp; unsigned int __user *up = argp; - unsigned int u; + unsigned short u; int __user *sp = argp; int s; int ret; @@ -1026,7 +1026,7 @@ static long macvtap_ioctl(struct file *file, unsigned int cmd, if ((u & ~MACVTAP_FEATURES) != (IFF_NO_PI | IFF_TAP)) ret = -EINVAL; else - q->flags = u; + q->flags = (q->flags & ~MACVTAP_FEATURES) | u; return ret; @@ -1039,8 +1039,9 @@ static long macvtap_ioctl(struct file *file, unsigned int cmd, } ret = 0; + u = q->flags; if (copy_to_user(&ifr->ifr_name, vlan->dev->name, IFNAMSIZ) || - put_user(q->flags, &ifr->ifr_flags)) + put_user(u, &ifr->ifr_flags)) ret = -EFAULT; macvtap_put_vlan(vlan); rtnl_unlock(); -- MST -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
