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net: dst: annotate data-races around dst->input

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dst_dev_put() can overwrite dst->input while other
cpus might read this field (for instance from dst_input())

Add READ_ONCE()/WRITE_ONCE() annotations to suppress
potential issues.

We will likely need full RCU protection later.

Fixes: 4a6ce2b6f2 ("net: introduce a new function dst_dev_put()")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Kuniyuki Iwashima <kuniyu@google.com>
Link: https://patch.msgid.link/20250630121934.3399505-5-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Eric Dumazet
2025-06-30 12:19:28 +00:00
committed by Jakub Kicinski
parent 8f2b2282d0
commit f1c5fd3489
4 changed files with 5 additions and 5 deletions
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2
include/net/dst.h
View File

@@ -468,7 +468,7 @@ INDIRECT_CALLABLE_DECLARE(int ip_local_deliver(struct sk_buff *));
/* Input packet from network to transport. */
static inline int dst_input(struct sk_buff *skb)
{
return INDIRECT_CALL_INET(skb_dst(skb)->input,
return INDIRECT_CALL_INET(READ_ONCE(skb_dst(skb)->input),
ip6_input, ip_local_deliver, skb);
}

4
include/net/lwtunnel.h
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@@ -142,8 +142,8 @@ static inline void lwtunnel_set_redirect(struct dst_entry *dst)
dst->output = lwtunnel_output;
}
if (lwtunnel_input_redirect(dst->lwtstate)) {
dst->lwtstate->orig_input = dst->input;
dst->input = lwtunnel_input;
dst->lwtstate->orig_input = READ_ONCE(dst->input);
WRITE_ONCE(dst->input, lwtunnel_input);
}
}
#else

2
net/core/dst.c
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@@ -148,7 +148,7 @@ void dst_dev_put(struct dst_entry *dst)
WRITE_ONCE(dst->obsolete, DST_OBSOLETE_DEAD);
if (dst->ops->ifdown)
dst->ops->ifdown(dst, dev);
dst->input = dst_discard;
WRITE_ONCE(dst->input, dst_discard);
dst->output = dst_discard_out;
dst->dev = blackhole_netdev;
netdev_ref_replace(dev, blackhole_netdev, &dst->dev_tracker,

2
net/ipv4/route.c
View File

@@ -1687,7 +1687,7 @@ struct rtable *rt_dst_clone(struct net_device *dev, struct rtable *rt)
else if (rt->rt_gw_family == AF_INET6)
new_rt->rt_gw6 = rt->rt_gw6;
new_rt->dst.input = rt->dst.input;
new_rt->dst.input = READ_ONCE(rt->dst.input);
new_rt->dst.output = rt->dst.output;
new_rt->dst.error = rt->dst.error;
new_rt->dst.lastuse = jiffies;