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Commit 39ec7de7 authored by Michael S. Tsirkin's avatar Michael S. Tsirkin Committed by David S. Miller
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macvtap: fix uninitialized access on TUNSETIFF 



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: default avatarMichael S. Tsirkin <mst@redhat.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent c286bbaf

drivers/net/macvtap.c

+4 −3
Original line number Diff line number Diff line
@@ -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();