4.19-stable review patch. If anyone has any objections, please let me know.
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From: Eric Dumazet edumazet@google.com
[ Upstream commit cf28ff8e4c02e1ffa850755288ac954b6ff0db8c ]
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.
ila_output() is called from lwtunnel_output() possibly from process context, and under rcu_read_lock().
We might be interrupted by a softirq, re-enter ila_output() and corrupt dst_cache data structures.
Fix the race by using local_bh_disable().
Signed-off-by: Eric Dumazet edumazet@google.com Acked-by: Paolo Abeni pabeni@redhat.com Link: https://lore.kernel.org/r/20240531132636.2637995-5-edumazet@google.com Signed-off-by: Jakub Kicinski kuba@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- net/ipv6/ila/ila_lwt.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-)
diff --git a/net/ipv6/ila/ila_lwt.c b/net/ipv6/ila/ila_lwt.c index 3d56a2fb6f86f..c7630776bd8e8 100644 --- a/net/ipv6/ila/ila_lwt.c +++ b/net/ipv6/ila/ila_lwt.c @@ -58,7 +58,9 @@ static int ila_output(struct net *net, struct sock *sk, struct sk_buff *skb) return orig_dst->lwtstate->orig_output(net, sk, skb); }
+ local_bh_disable(); dst = dst_cache_get(&ilwt->dst_cache); + local_bh_enable(); if (unlikely(!dst)) { struct ipv6hdr *ip6h = ipv6_hdr(skb); struct flowi6 fl6; @@ -86,8 +88,11 @@ static int ila_output(struct net *net, struct sock *sk, struct sk_buff *skb) goto drop; }
- if (ilwt->connected) + if (ilwt->connected) { + local_bh_disable(); dst_cache_set_ip6(&ilwt->dst_cache, dst, &fl6.saddr); + local_bh_enable(); + } }
skb_dst_set(skb, dst);