6.12-stable review patch. If anyone has any objections, please let me know.
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From: Justin Iurman justin.iurman@uliege.be
[ Upstream commit c03a49f3093a4903c8a93c8b5c9a297b5343b169 ]
In lwtunnel_{output|xmit}(), dev_xmit_recursion() may be called in preemptible scope for PREEMPT kernels. This patch disables BHs before calling dev_xmit_recursion(). BHs are re-enabled only at the end, since we must ensure the same CPU is used for both dev_xmit_recursion_inc() and dev_xmit_recursion_dec() (and any other recursion levels in some cases) in order to maintain valid per-cpu counters.
Reported-by: Alexei Starovoitov alexei.starovoitov@gmail.com Closes: https://lore.kernel.org/netdev/CAADnVQJFWn3dBFJtY+ci6oN1pDFL=TzCmNbRgey7MdYx... Reported-by: Eduard Zingerman eddyz87@gmail.com Closes: https://lore.kernel.org/netdev/m2h62qwf34.fsf@gmail.com/ Fixes: 986ffb3a57c5 ("net: lwtunnel: fix recursion loops") Signed-off-by: Justin Iurman justin.iurman@uliege.be Reviewed-by: Simon Horman horms@kernel.org Link: https://patch.msgid.link/20250416160716.8823-1-justin.iurman@uliege.be Signed-off-by: Paolo Abeni pabeni@redhat.com Signed-off-by: Sasha Levin sashal@kernel.org --- net/core/lwtunnel.c | 26 ++++++++++++++++++++------ 1 file changed, 20 insertions(+), 6 deletions(-)
diff --git a/net/core/lwtunnel.c b/net/core/lwtunnel.c index 4417a18b3e951..f63586c9ce021 100644 --- a/net/core/lwtunnel.c +++ b/net/core/lwtunnel.c @@ -332,6 +332,8 @@ int lwtunnel_output(struct net *net, struct sock *sk, struct sk_buff *skb) struct dst_entry *dst; int ret;
+ local_bh_disable(); + if (dev_xmit_recursion()) { net_crit_ratelimited("%s(): recursion limit reached on datapath\n", __func__); @@ -347,8 +349,10 @@ int lwtunnel_output(struct net *net, struct sock *sk, struct sk_buff *skb) lwtstate = dst->lwtstate;
if (lwtstate->type == LWTUNNEL_ENCAP_NONE || - lwtstate->type > LWTUNNEL_ENCAP_MAX) - return 0; + lwtstate->type > LWTUNNEL_ENCAP_MAX) { + ret = 0; + goto out; + }
ret = -EOPNOTSUPP; rcu_read_lock(); @@ -363,11 +367,13 @@ int lwtunnel_output(struct net *net, struct sock *sk, struct sk_buff *skb) if (ret == -EOPNOTSUPP) goto drop;
- return ret; + goto out;
drop: kfree_skb(skb);
+out: + local_bh_enable(); return ret; } EXPORT_SYMBOL_GPL(lwtunnel_output); @@ -379,6 +385,8 @@ int lwtunnel_xmit(struct sk_buff *skb) struct dst_entry *dst; int ret;
+ local_bh_disable(); + if (dev_xmit_recursion()) { net_crit_ratelimited("%s(): recursion limit reached on datapath\n", __func__); @@ -395,8 +403,10 @@ int lwtunnel_xmit(struct sk_buff *skb) lwtstate = dst->lwtstate;
if (lwtstate->type == LWTUNNEL_ENCAP_NONE || - lwtstate->type > LWTUNNEL_ENCAP_MAX) - return 0; + lwtstate->type > LWTUNNEL_ENCAP_MAX) { + ret = 0; + goto out; + }
ret = -EOPNOTSUPP; rcu_read_lock(); @@ -411,11 +421,13 @@ int lwtunnel_xmit(struct sk_buff *skb) if (ret == -EOPNOTSUPP) goto drop;
- return ret; + goto out;
drop: kfree_skb(skb);
+out: + local_bh_enable(); return ret; } EXPORT_SYMBOL_GPL(lwtunnel_xmit); @@ -427,6 +439,8 @@ int lwtunnel_input(struct sk_buff *skb) struct dst_entry *dst; int ret;
+ DEBUG_NET_WARN_ON_ONCE(!in_softirq()); + if (dev_xmit_recursion()) { net_crit_ratelimited("%s(): recursion limit reached on datapath\n", __func__);