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neighbour: use RCU protection in __neigh_notify()

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__neigh_notify() can be called without RTNL or RCU protection.

Use RCU protection to avoid potential UAF.

Fixes: 426b5303eb ("[NETNS]: Modify the neighbour table code so it handles multiple network namespaces")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: David Ahern <dsahern@kernel.org>
Reviewed-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Link: https://patch.msgid.link/20250207135841.1948589-4-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Eric Dumazet 2025-02-07 13:58:35 +00:00 • committed by Jakub Kicinski
parent 628e6d1893
commit becbd5850c
1 changed files with 6 additions and 2 deletions
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8
net/core/neighbour.c
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@ -3447,10 +3447,12 @@ static const struct seq_operations neigh_stat_seq_ops = {
static void __neigh_notify(struct neighbour *n, int type, int flags, static void __neigh_notify(struct neighbour *n, int type, int flags,
u32 pid) u32 pid)
{ {
struct net *net = dev_net(n->dev);
struct sk_buff *skb; struct sk_buff *skb;
int err = -ENOBUFS; int err = -ENOBUFS;
struct net *net;
rcu_read_lock();
net = dev_net_rcu(n->dev);
skb = nlmsg_new(neigh_nlmsg_size(), GFP_ATOMIC); skb = nlmsg_new(neigh_nlmsg_size(), GFP_ATOMIC);
if (skb == NULL) if (skb == NULL)
goto errout; goto errout;
@ -3463,9 +3465,11 @@ static void __neigh_notify(struct neighbour *n, int type, int flags,
goto errout; goto errout;
} }
rtnl_notify(skb, net, 0, RTNLGRP_NEIGH, NULL, GFP_ATOMIC); rtnl_notify(skb, net, 0, RTNLGRP_NEIGH, NULL, GFP_ATOMIC);
return; goto out;
errout: errout:
rtnl_set_sk_err(net, RTNLGRP_NEIGH, err); rtnl_set_sk_err(net, RTNLGRP_NEIGH, err);
out:
rcu_read_unlock();
} }
void neigh_app_ns(struct neighbour *n) void neigh_app_ns(struct neighbour *n)