From a35d310f03a692bf4798eb309a1950a06a150620 Mon Sep 17 00:00:00 2001 From: Jason Wang Date: Wed, 8 May 2019 23:20:17 -0400 Subject: [PATCH] tuntap: fix dividing by zero in ebpf queue selection We need check if tun->numqueues is zero (e.g for the persist device) before trying to use it for modular arithmetic. Reported-by: Eric Dumazet Fixes: 96f84061620c6("tun: add eBPF based queue selection method") Signed-off-by: Jason Wang Reviewed-by: Eric Dumazet Signed-off-by: David S. Miller --- drivers/net/tun.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/drivers/net/tun.c b/drivers/net/tun.c index 9d72f8c76c15..a52bd47e7aa2 100644 --- a/drivers/net/tun.c +++ b/drivers/net/tun.c @@ -596,13 +596,18 @@ static u16 tun_automq_select_queue(struct tun_struct *tun, struct sk_buff *skb) static u16 tun_ebpf_select_queue(struct tun_struct *tun, struct sk_buff *skb) { struct tun_prog *prog; + u32 numqueues; u16 ret = 0; + numqueues = READ_ONCE(tun->numqueues); + if (!numqueues) + return 0; + prog = rcu_dereference(tun->steering_prog); if (prog) ret = bpf_prog_run_clear_cb(prog->prog, skb); - return ret % tun->numqueues; + return ret % numqueues; } static u16 tun_select_queue(struct net_device *dev, struct sk_buff *skb, -- 2.25.1