diff options
| author | Cong Wang <xiyou.wangcong@gmail.com> | 2018-12-29 13:56:36 -0800 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2018-12-30 14:07:54 -0800 |
| commit | c433570458e49bccea5c551df628d058b3526289 (patch) | |
| tree | 05427f71af7a74fb15b0eb08f138cc6004a225c1 | |
| parent | 7f334a7e1ae113212e39aafba51352ea9ab8c9f9 (diff) | |
ax25: fix a use-after-free in ax25_fillin_cb()
There are multiple issues here:
1. After freeing dev->ax25_ptr, we need to set it to NULL otherwise
we may use a dangling pointer.
2. There is a race between ax25_setsockopt() and device notifier as
reported by syzbot. Close it by holding RTNL lock.
3. We need to test if dev->ax25_ptr is NULL before using it.
Reported-and-tested-by: syzbot+ae6bb869cbed29b29040@syzkaller.appspotmail.com
Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
| -rw-r--r-- | net/ax25/af_ax25.c | 11 | ||||
| -rw-r--r-- | net/ax25/ax25_dev.c | 2 |
2 files changed, 11 insertions, 2 deletions
diff --git a/net/ax25/af_ax25.c b/net/ax25/af_ax25.c index c603d33d5410..5d01edf8d819 100644 --- a/net/ax25/af_ax25.c +++ b/net/ax25/af_ax25.c @@ -653,15 +653,22 @@ static int ax25_setsockopt(struct socket *sock, int level, int optname, break; } - dev = dev_get_by_name(&init_net, devname); + rtnl_lock(); + dev = __dev_get_by_name(&init_net, devname); if (!dev) { + rtnl_unlock(); res = -ENODEV; break; } ax25->ax25_dev = ax25_dev_ax25dev(dev); + if (!ax25->ax25_dev) { + rtnl_unlock(); + res = -ENODEV; + break; + } ax25_fillin_cb(ax25, ax25->ax25_dev); - dev_put(dev); + rtnl_unlock(); break; default: diff --git a/net/ax25/ax25_dev.c b/net/ax25/ax25_dev.c index 9a3a301e1e2f..d92195cd7834 100644 --- a/net/ax25/ax25_dev.c +++ b/net/ax25/ax25_dev.c @@ -116,6 +116,7 @@ void ax25_dev_device_down(struct net_device *dev) if ((s = ax25_dev_list) == ax25_dev) { ax25_dev_list = s->next; spin_unlock_bh(&ax25_dev_lock); + dev->ax25_ptr = NULL; dev_put(dev); kfree(ax25_dev); return; @@ -125,6 +126,7 @@ void ax25_dev_device_down(struct net_device *dev) if (s->next == ax25_dev) { s->next = ax25_dev->next; spin_unlock_bh(&ax25_dev_lock); + dev->ax25_ptr = NULL; dev_put(dev); kfree(ax25_dev); return; |