From: Eric Dumazet Date: Tue, 1 Feb 2022 01:21:06 +0000 (-0800) Subject: rtnetlink: make sure to refresh master_dev/m_ops in __rtnl_newlink() X-Git-Tag: v4.19.228~35 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=a01e60a1ec6bef9be471fb7182a33c6d6f124e93;p=thirdparty%2Fkernel%2Fstable.git 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: ba7d49b1f0f8 ("rtnetlink: provide api for getting and setting slave info") Signed-off-by: Eric Dumazet Cc: Jiri Pirko Link: https://lore.kernel.org/r/20220201012106.216495-1-eric.dumazet@gmail.com Signed-off-by: Jakub Kicinski Signed-off-by: Greg Kroah-Hartman --- diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c index 907dd0c7e8a66..2837cc03f69e2 100644 --- a/net/core/rtnetlink.c +++ b/net/core/rtnetlink.c @@ -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)