@@ -333,6 +333,8 @@ 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__);
@@ -348,8 +350,10 @@ 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();
@@ -364,11 +368,13 @@ 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);
@@ -380,6 +386,8 @@ 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__);
@@ -396,8 +404,10 @@ 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();
@@ -412,11 +422,13 @@ 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);
@@ -428,6 +440,8 @@ 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__);
v3: - removed unrelated code cleanups v2: - https://lore.kernel.org/netdev/20250415173239.39781-1-justin.iurman@uliege.be/ v1: - https://lore.kernel.org/netdev/20250403083956.13946-1-justin.iurman@uliege.be/ 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=TzCmNbRgey7MdYxt_AP2g@mail.gmail.com/ 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> --- Cc: bpf <bpf@vger.kernel.org> Cc: Alexei Starovoitov <alexei.starovoitov@gmail.com> Cc: Stanislav Fomichev <stfomichev@gmail.com> Cc: Sebastian Sewior <bigeasy@linutronix.de> Cc: Andrea Mayer <andrea.mayer@uniroma2.it> Cc: Stefano Salsano <stefano.salsano@uniroma2.it> Cc: Paolo Lungaroni <paolo.lungaroni@uniroma2.it> --- net/core/lwtunnel.c | 26 ++++++++++++++++++++------ 1 file changed, 20 insertions(+), 6 deletions(-)