diff options
| author | Cong Wang <cong.wang@bytedance.com> | 2021-02-11 11:34:10 -0800 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2021-02-11 18:14:19 -0800 |
| commit | 3b23a32a63219f51a5298bc55a65ecee866e79d0 (patch) | |
| tree | 79f9a923b4679addfc28e39340e9834b922f7e40 /drivers/net/tap.c | |
| parent | 7867299cde34e9c2d2c676f2a384a9d5853b914d (diff) | |
net: fix dev_ifsioc_locked() race condition
dev_ifsioc_locked() is called with only RCU read lock, so when
there is a parallel writer changing the mac address, it could
get a partially updated mac address, as shown below:
Thread 1 Thread 2
// eth_commit_mac_addr_change()
memcpy(dev->dev_addr, addr->sa_data, ETH_ALEN);
// dev_ifsioc_locked()
memcpy(ifr->ifr_hwaddr.sa_data,
dev->dev_addr,...);
Close this race condition by guarding them with a RW semaphore,
like netdev_get_name(). We can not use seqlock here as it does not
allow blocking. The writers already take RTNL anyway, so this does
not affect the slow path. To avoid bothering existing
dev_set_mac_address() callers in drivers, introduce a new wrapper
just for user-facing callers on ioctl and rtnetlink paths.
Note, bonding also changes slave mac addresses but that requires
a separate patch due to the complexity of bonding code.
Fixes: 3710becf8a58 ("net: RCU locking for simple ioctl()")
Reported-by: "Gong, Sishuai" <sishuai@purdue.edu>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Cong Wang <cong.wang@bytedance.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'drivers/net/tap.c')
| -rw-r--r-- | drivers/net/tap.c | 7 |
1 files changed, 3 insertions, 4 deletions
diff --git a/drivers/net/tap.c b/drivers/net/tap.c index ff4aa35979a1..8e3a28ba6b28 100644 --- a/drivers/net/tap.c +++ b/drivers/net/tap.c @@ -1090,10 +1090,9 @@ static long tap_ioctl(struct file *file, unsigned int cmd, return -ENOLINK; } ret = 0; - u = tap->dev->type; + dev_get_mac_address(&sa, dev_net(tap->dev), tap->dev->name); if (copy_to_user(&ifr->ifr_name, tap->dev->name, IFNAMSIZ) || - copy_to_user(&ifr->ifr_hwaddr.sa_data, tap->dev->dev_addr, ETH_ALEN) || - put_user(u, &ifr->ifr_hwaddr.sa_family)) + copy_to_user(&ifr->ifr_hwaddr, &sa, sizeof(sa))) ret = -EFAULT; tap_put_tap_dev(tap); rtnl_unlock(); @@ -1108,7 +1107,7 @@ static long tap_ioctl(struct file *file, unsigned int cmd, rtnl_unlock(); return -ENOLINK; } - ret = dev_set_mac_address(tap->dev, &sa, NULL); + ret = dev_set_mac_address_user(tap->dev, &sa, NULL); tap_put_tap_dev(tap); rtnl_unlock(); return ret; |