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authorEric Dumazet <edumazet@google.com>2022-01-31 17:21:06 -0800
committerJakub Kicinski <kuba@kernel.org>2022-02-01 20:19:00 -0800
commitc6f6f2444bdbe0079e41914a35081530d0409963 (patch)
treea092807eddace8b3d89c808d4f65071057bfb8e1 /net/core
parent04c2a47ffb13c29778e2a14e414ad4cb5a5db4b5 (diff)
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rtnetlink: make sure to refresh master_dev/m_ops in __rtnl_newlink()
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>
Diffstat (limited to 'net/core')
-rw-r--r--net/core/rtnetlink.c6
1 files changed, 4 insertions, 2 deletions
diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c
index e476403231f0..710da8a36729 100644
--- a/net/core/rtnetlink.c
+++ b/net/core/rtnetlink.c
@@ -3275,8 +3275,8 @@ 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];
@@ -3314,6 +3314,8 @@ replay:
else
dev = NULL;
+ master_dev = NULL;
+ m_ops = NULL;
if (dev) {
master_dev = netdev_master_upper_dev_get(dev);
if (master_dev)