6.12-stable review patch. If anyone has any objections, please let me know.
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From: Eric Dumazet edumazet@google.com
[ Upstream commit f1c5fd34891a1c242885f48c2e4dc52df180f311 ]
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: 4a6ce2b6f2ec ("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 Signed-off-by: Sasha Levin sashal@kernel.org --- include/net/dst.h | 2 +- include/net/lwtunnel.h | 4 ++-- net/core/dst.c | 2 +- net/ipv4/route.c | 2 +- 4 files changed, 5 insertions(+), 5 deletions(-)
diff --git a/include/net/dst.h b/include/net/dst.h index 08647c99d79c..c844ba143b9c 100644 --- a/include/net/dst.h +++ b/include/net/dst.h @@ -466,7 +466,7 @@ 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); }
diff --git a/include/net/lwtunnel.h b/include/net/lwtunnel.h index 53bd2d02a4f0..a4632a64daae 100644 --- a/include/net/lwtunnel.h +++ b/include/net/lwtunnel.h @@ -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 diff --git a/net/core/dst.c b/net/core/dst.c index 6d76b799ce64..0eef85f8f1f3 100644 --- a/net/core/dst.c +++ b/net/core/dst.c @@ -148,7 +148,7 @@ void dst_dev_put(struct dst_entry *dst) 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, diff --git a/net/ipv4/route.c b/net/ipv4/route.c index 88d7c96bfac0..118f01aef868 100644 --- a/net/ipv4/route.c +++ b/net/ipv4/route.c @@ -1684,7 +1684,7 @@ 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;