[net,V3,1/2] tuntap: fix dividing by zero in ebpf queue selection
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Message ID 1557372018-18544-1-git-send-email-jasowang@redhat.com
State Accepted
Commit a35d310f03a692bf4798eb309a1950a06a150620
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  • [net,V3,1/2] tuntap: fix dividing by zero in ebpf queue selection
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Commit Message

Jason Wang May 9, 2019, 3:20 a.m. UTC
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 <eric.dumazet@gmail.com>
Fixes: 96f84061620c6("tun: add eBPF based queue selection method")
Signed-off-by: Jason Wang <jasowang@redhat.com>
---
 drivers/net/tun.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

Comments

Eric Dumazet May 9, 2019, 11:35 a.m. UTC | #1
On 5/8/19 11:20 PM, Jason Wang wrote:
> 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 <eric.dumazet@gmail.com>
> Fixes: 96f84061620c6("tun: add eBPF based queue selection method")
> Signed-off-by: Jason Wang <jasowang@redhat.com>
> ---

Reviewed-by: Eric Dumazet <edumazet@google.com>

Thanks.
David Miller May 9, 2019, 4:22 p.m. UTC | #2
From: Jason Wang <jasowang@redhat.com>
Date: Wed,  8 May 2019 23:20:17 -0400

> 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 <eric.dumazet@gmail.com>
> Fixes: 96f84061620c6("tun: add eBPF based queue selection method")
> Signed-off-by: Jason Wang <jasowang@redhat.com>

Applied and queued up for -stable.

Patch
diff mbox series

diff --git a/drivers/net/tun.c b/drivers/net/tun.c
index e9ca1c0..dc62fc3 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,