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| author | Eric Dumazet <edumazet@google.com> | 2024-05-31 13:26:34 +0000 |
|---|---|---|
| committer | Jakub Kicinski <kuba@kernel.org> | 2024-06-03 18:50:08 -0700 |
| commit | c0b98ac1cc104f48763cdb27b1e9ac25fd81fc90 (patch) | |
| tree | 47bf3586373335218130b8daac1fc50b85a38955 | |
| parent | db0090c6eb12c31246438b7fe2a8f1b833e7a653 (diff) | |
| download | lwn-c0b98ac1cc104f48763cdb27b1e9ac25fd81fc90.tar.gz lwn-c0b98ac1cc104f48763cdb27b1e9ac25fd81fc90.zip | |
ipv6: sr: block BH in seg6_output_core() and seg6_input_core()
As explained in commit 1378817486d6 ("tipc: block BH
before using dst_cache"), net/core/dst_cache.c
helpers need to be called with BH disabled.
Disabling preemption in seg6_output_core() is not good enough,
because seg6_output_core() is called from process context,
lwtunnel_output() only uses rcu_read_lock().
We might be interrupted by a softirq, re-enter seg6_output_core()
and corrupt dst_cache data structures.
Fix the race by using local_bh_disable() instead of
preempt_disable().
Apply a similar change in seg6_input_core().
Fixes: fa79581ea66c ("ipv6: sr: fix several BUGs when preemption is enabled")
Fixes: 6c8702c60b88 ("ipv6: sr: add support for SRH encapsulation and injection with lwtunnels")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: David Lebrun <dlebrun@google.com>
Acked-by: Paolo Abeni <pabeni@redhat.com>
Link: https://lore.kernel.org/r/20240531132636.2637995-4-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
| -rw-r--r-- | net/ipv6/seg6_iptunnel.c | 14 |
1 files changed, 6 insertions, 8 deletions
diff --git a/net/ipv6/seg6_iptunnel.c b/net/ipv6/seg6_iptunnel.c index a75df2ec8db0..098632adc9b5 100644 --- a/net/ipv6/seg6_iptunnel.c +++ b/net/ipv6/seg6_iptunnel.c @@ -464,23 +464,21 @@ static int seg6_input_core(struct net *net, struct sock *sk, slwt = seg6_lwt_lwtunnel(orig_dst->lwtstate); - preempt_disable(); + local_bh_disable(); dst = dst_cache_get(&slwt->cache); - preempt_enable(); if (!dst) { ip6_route_input(skb); dst = skb_dst(skb); if (!dst->error) { - preempt_disable(); dst_cache_set_ip6(&slwt->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)) @@ -536,9 +534,9 @@ static int seg6_output_core(struct net *net, struct sock *sk, slwt = seg6_lwt_lwtunnel(orig_dst->lwtstate); - preempt_disable(); + local_bh_disable(); dst = dst_cache_get(&slwt->cache); - preempt_enable(); + local_bh_enable(); if (unlikely(!dst)) { struct ipv6hdr *hdr = ipv6_hdr(skb); @@ -558,9 +556,9 @@ static int seg6_output_core(struct net *net, struct sock *sk, goto drop; } - preempt_disable(); + local_bh_disable(); dst_cache_set_ip6(&slwt->cache, dst, &fl6.saddr); - preempt_enable(); + local_bh_enable(); } skb_dst_drop(skb); |