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net: ipv6: rpl_iptunnel: block BH in rpl_output() and rpl_input()

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As explained in commit 1378817486 ("tipc: block BH
before using dst_cache"), net/core/dst_cache.c
helpers need to be called with BH disabled.

Disabling preemption in rpl_output() is not good enough,
because rpl_output() is called from process context,
lwtunnel_output() only uses rcu_read_lock().

We might be interrupted by a softirq, re-enter rpl_output()
and corrupt dst_cache data structures.

Fix the race by using local_bh_disable() instead of
preempt_disable().

Apply a similar change in rpl_input().

Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Alexander Aring <aahringo@redhat.com>
Acked-by: Paolo Abeni <pabeni@redhat.com>
Link: https://lore.kernel.org/r/20240531132636.2637995-3-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Eric Dumazet 2024-05-31 13:26:33 +00:00 committed by Jakub Kicinski
parent 2fe40483ec
commit db0090c6eb
1 changed files with 6 additions and 8 deletions
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14
net/ipv6/rpl_iptunnel.c
View File

@ -212,9 +212,9 @@ static int rpl_output(struct net *net, struct sock *sk, struct sk_buff *skb)
if (unlikely(err))
goto drop;
preempt_disable();
local_bh_disable();
dst = dst_cache_get(&rlwt->cache);
preempt_enable();
local_bh_enable();
if (unlikely(!dst)) {
struct ipv6hdr *hdr = ipv6_hdr(skb);
@ -234,9 +234,9 @@ static int rpl_output(struct net *net, struct sock *sk, struct sk_buff *skb)
goto drop;
}
preempt_disable();
local_bh_disable();
dst_cache_set_ip6(&rlwt->cache, dst, &fl6.saddr);
preempt_enable();
local_bh_enable();
}
skb_dst_drop(skb);
@ -268,23 +268,21 @@ static int rpl_input(struct sk_buff *skb)
return err;
}
preempt_disable();
local_bh_disable();
dst = dst_cache_get(&rlwt->cache);
preempt_enable();
if (!dst) {
ip6_route_input(skb);
dst = skb_dst(skb);
if (!dst->error) {
preempt_disable();
dst_cache_set_ip6(&rlwt->cache, dst,
&ipv6_hdr(skb)->saddr);
preempt_enable();
}
} else {
skb_dst_drop(skb);
skb_dst_set(skb, dst);
}
local_bh_enable();
err = skb_cow_head(skb, LL_RESERVED_SPACE(dst->dev));
if (unlikely(err))