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Commit d707a4f8 authored by Eric Dumazet's avatar Eric Dumazet Committed by Pavel Machek
Browse files

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



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: ba7d49b1 ("rtnetlink: provide api for getting and setting slave info")
Signed-off-by: default avatarEric 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: default avatarJakub Kicinski <kuba@kernel.org>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 9bf0b2cf

net/core/rtnetlink.c

+4 −2
Original line number Diff line number Diff line
@@ -2198,9 +2198,9 @@ 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];
@@ -2231,6 +2231,8 @@ replay: 
			dev = NULL;

	}



	master_dev = NULL;

	m_ops = NULL;

	if (dev) {

		master_dev = netdev_master_upper_dev_get(dev);

		if (master_dev)