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rtnetlink: make sure to refresh master_dev/m_ops in __rtnl_newlink()

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commit c6f6f2444bdbe0079e41914a35081530d0409963 upstream.

While looking at one unrelated syzbot bug, I found the replay logic
in __rtnl_newlink() to potentially trigger use-after-free.

It is better to clear master_dev and m_ops inside the loop,
in case we have to replay it.

Fixes: ba7d49b1f0 ("rtnetlink: provide api for getting and setting slave info")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Jiri Pirko <jiri@nvidia.com>
Link: https://lore.kernel.org/r/20220201012106.216495-1-eric.dumazet@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Eric Dumazet 2022-01-31 17:21:06 -08:00 committed by Greg Kroah-Hartman
parent 34aeb4da20
commit a01e60a1ec
1 changed files with 4 additions and 2 deletions
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6
net/core/rtnetlink.c
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@ -2942,9 +2942,9 @@ static int rtnl_newlink(struct sk_buff *skb, struct nlmsghdr *nlh,
{
struct net *net = sock_net(skb->sk);
const struct rtnl_link_ops *ops;
const struct rtnl_link_ops *m_ops = NULL;
const struct rtnl_link_ops *m_ops;
struct net_device *dev;
struct net_device *master_dev = NULL;
struct net_device *master_dev;
struct ifinfomsg *ifm;
char kind[MODULE_NAME_LEN];
char ifname[IFNAMSIZ];
@ -2979,6 +2979,8 @@ replay:
dev = NULL;
}
master_dev = NULL;
m_ops = NULL;
if (dev) {
master_dev = netdev_master_upper_dev_get(dev);
if (master_dev)