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authorNikolay Aleksandrov <nikolay@nvidia.com>2021-08-05 11:29:01 +0300
committerDavid S. Miller <davem@davemloft.net>2021-08-05 11:36:59 +0100
commit893b195875340cb44b54c9db99e708145f1210e8 (patch)
treef5d98a9ed881302ccbbb53865b82f7d7e9fb8b6a /net/bridge/br_ioctl.c
parent4167a960574fcadc9067f4280951a35b8c021c68 (diff)
net: bridge: fix ioctl locking
Before commit ad2f99aedf8f ("net: bridge: move bridge ioctls out of .ndo_do_ioctl") the bridge ioctl calls were divided in two parts: one was deviceless called by sock_ioctl and didn't expect rtnl to be held, the other was with a device called by dev_ifsioc() and expected rtnl to be held. After the commit above they were united in a single ioctl stub, but it didn't take care of the locking expectations. For sock_ioctl now we acquire (1) br_ioctl_mutex, (2) rtnl and for dev_ifsioc we acquire (1) rtnl, (2) br_ioctl_mutex The fix is to get a refcnt on the netdev for dev_ifsioc calls and drop rtnl then to reacquire it in the bridge ioctl stub after br_ioctl_mutex has been acquired. That will avoid playing locking games and make the rules straight-forward: we always take br_ioctl_mutex first, and then rtnl. Reported-by: syzbot+34fe5894623c4ab1b379@syzkaller.appspotmail.com Fixes: ad2f99aedf8f ("net: bridge: move bridge ioctls out of .ndo_do_ioctl") Signed-off-by: Nikolay Aleksandrov <nikolay@nvidia.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/bridge/br_ioctl.c')
-rw-r--r--net/bridge/br_ioctl.c37
1 files changed, 24 insertions, 13 deletions
diff --git a/net/bridge/br_ioctl.c b/net/bridge/br_ioctl.c
index 46a24c20e405..2f848de3e755 100644
--- a/net/bridge/br_ioctl.c
+++ b/net/bridge/br_ioctl.c
@@ -369,33 +369,44 @@ static int old_deviceless(struct net *net, void __user *uarg)
int br_ioctl_stub(struct net *net, struct net_bridge *br, unsigned int cmd,
struct ifreq *ifr, void __user *uarg)
{
+ int ret = -EOPNOTSUPP;
+
+ rtnl_lock();
+
switch (cmd) {
case SIOCGIFBR:
case SIOCSIFBR:
- return old_deviceless(net, uarg);
-
+ ret = old_deviceless(net, uarg);
+ break;
case SIOCBRADDBR:
case SIOCBRDELBR:
{
char buf[IFNAMSIZ];
- if (!ns_capable(net->user_ns, CAP_NET_ADMIN))
- return -EPERM;
+ if (!ns_capable(net->user_ns, CAP_NET_ADMIN)) {
+ ret = -EPERM;
+ break;
+ }
- if (copy_from_user(buf, uarg, IFNAMSIZ))
- return -EFAULT;
+ if (copy_from_user(buf, uarg, IFNAMSIZ)) {
+ ret = -EFAULT;
+ break;
+ }
buf[IFNAMSIZ-1] = 0;
if (cmd == SIOCBRADDBR)
- return br_add_bridge(net, buf);
-
- return br_del_bridge(net, buf);
+ ret = br_add_bridge(net, buf);
+ else
+ ret = br_del_bridge(net, buf);
}
-
+ break;
case SIOCBRADDIF:
case SIOCBRDELIF:
- return add_del_if(br, ifr->ifr_ifindex, cmd == SIOCBRADDIF);
-
+ ret = add_del_if(br, ifr->ifr_ifindex, cmd == SIOCBRADDIF);
+ break;
}
- return -EOPNOTSUPP;
+
+ rtnl_unlock();
+
+ return ret;
}