[PATCH 1/5] macvtap: fix uninitialized access on TUNSETIFF
From: "Michael S. Tsirkin" <mst@redhat.com>
Date: 2014-12-16 13:05:30
Also in:
lkml
Subsystem:
networking drivers, the rest · Maintainers:
Andrew Lunn, "David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Linus Torvalds
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(-)
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