6.11-stable review patch. If anyone has any objections, please let me know.
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From: Breno Leitao leitao@debian.org
[ Upstream commit 157f29152b61ca41809dd7ead29f5733adeced19 ]
During the introduction of struct bpf_net_context handling for XDP-redirect, the netkit driver has been missed, which also requires it because NETKIT_REDIRECT invokes skb_do_redirect() which is accessing the per-CPU variables. Otherwise we see the following crash:
BUG: kernel NULL pointer dereference, address: 0000000000000038 bpf_redirect() netkit_xmit() dev_hard_start_xmit()
Set the bpf_net_context before invoking netkit_xmit() program within the netkit driver.
Fixes: 401cb7dae813 ("net: Reference bpf_redirect_info via task_struct on PREEMPT_RT.") Signed-off-by: Breno Leitao leitao@debian.org Acked-by: Daniel Borkmann daniel@iogearbox.net Reviewed-by: Sebastian Andrzej Siewior bigeasy@linutronix.de Reviewed-by: Toke Høiland-Jørgensen toke@redhat.com Acked-by: Nikolay Aleksandrov razor@blackwall.org Acked-by: Martin KaFai Lau martin.lau@kernel.org Link: https://patch.msgid.link/20240912155620.1334587-1-leitao@debian.org Signed-off-by: Jakub Kicinski kuba@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/net/netkit.c | 3 +++ 1 file changed, 3 insertions(+)
diff --git a/drivers/net/netkit.c b/drivers/net/netkit.c index 16789cd446e9e..3f4187102e773 100644 --- a/drivers/net/netkit.c +++ b/drivers/net/netkit.c @@ -65,6 +65,7 @@ static struct netkit *netkit_priv(const struct net_device *dev)
static netdev_tx_t netkit_xmit(struct sk_buff *skb, struct net_device *dev) { + struct bpf_net_context __bpf_net_ctx, *bpf_net_ctx; struct netkit *nk = netkit_priv(dev); enum netkit_action ret = READ_ONCE(nk->policy); netdev_tx_t ret_dev = NET_XMIT_SUCCESS; @@ -72,6 +73,7 @@ static netdev_tx_t netkit_xmit(struct sk_buff *skb, struct net_device *dev) struct net_device *peer; int len = skb->len;
+ bpf_net_ctx = bpf_net_ctx_set(&__bpf_net_ctx); rcu_read_lock(); peer = rcu_dereference(nk->peer); if (unlikely(!peer || !(peer->flags & IFF_UP) || @@ -110,6 +112,7 @@ static netdev_tx_t netkit_xmit(struct sk_buff *skb, struct net_device *dev) break; } rcu_read_unlock(); + bpf_net_ctx_clear(bpf_net_ctx); return ret_dev; }