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macvtap: fix uninitialized access on TUNSETIFF

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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>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Michael S. Tsirkin 2014-12-16 15:04:56 +02:00 committed by David S. Miller
parent c286bbaf4f
commit 39ec7de709
1 changed files with 4 additions and 3 deletions
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7
drivers/net/macvtap.c
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@ -999,7 +999,7 @@ 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;
@ -1014,7 +1014,7 @@ 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;
@ -1027,8 +1027,9 @@ 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();