From: Eric Dumazet edumazet@google.com
stable inclusion from stable-v5.10.97 commit 3bbe2019dd12b8d13671ee6cda055d49637b4c39 bugzilla: https://gitee.com/openeuler/kernel/issues/I55O0O
Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=...
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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: ba7d49b1f0f8 ("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 Signed-off-by: Yu Liao liaoyu15@huawei.com Reviewed-by: Wei Li liwei391@huawei.com Signed-off-by: Zheng Zengkai zhengzengkai@huawei.com --- net/core/rtnetlink.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c index e08b506163f5..a9168db1deea 100644 --- a/net/core/rtnetlink.c +++ b/net/core/rtnetlink.c @@ -3238,8 +3238,8 @@ static int __rtnl_newlink(struct sk_buff *skb, struct nlmsghdr *nlh, struct nlattr *slave_attr[RTNL_SLAVE_MAX_TYPE + 1]; unsigned char name_assign_type = NET_NAME_USER; struct nlattr *linkinfo[IFLA_INFO_MAX + 1]; - const struct rtnl_link_ops *m_ops = NULL; - struct net_device *master_dev = NULL; + const struct rtnl_link_ops *m_ops; + struct net_device *master_dev; struct net *net = sock_net(skb->sk); const struct rtnl_link_ops *ops; struct nlattr *tb[IFLA_MAX + 1]; @@ -3277,6 +3277,8 @@ static int __rtnl_newlink(struct sk_buff *skb, struct nlmsghdr *nlh, else dev = NULL;
+ master_dev = NULL; + m_ops = NULL; if (dev) { master_dev = netdev_master_upper_dev_get(dev); if (master_dev)