@@ -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();
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 <mst@redhat.com> --- drivers/net/macvtap.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-)