Commit 59cbf56f authored by Eric Dumazet's avatar Eric Dumazet Committed by David S. Miller

vxlan: test dev->flags & IFF_UP before calling gro_cells_receive()

Same reasons than the ones explained in commit 4179cb5a
("vxlan: test dev->flags & IFF_UP before calling netif_rx()")

netif_rx() or gro_cells_receive() must be called under a strict contract.

At device dismantle phase, core networking clears IFF_UP
and flush_all_backlogs() is called after rcu grace period
to make sure no incoming packet might be in a cpu backlog
and still referencing the device.

A similar protocol is used for gro_cells infrastructure, as
gro_cells_destroy() will be called only after a full rcu
grace period is observed after IFF_UP has been cleared.

Most drivers call netif_rx() from their interrupt handler,
and since the interrupts are disabled at device dismantle,
netif_rx() does not have to check dev->flags & IFF_UP

Virtual drivers do not have this guarantee, and must
therefore make the check themselves.

Otherwise we risk use-after-free and/or crashes.

Fixes: d342894c ("vxlan: virtual extensible lan")
Signed-off-by: default avatarEric Dumazet <edumazet@google.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 95d6ebd5
...@@ -1731,6 +1731,14 @@ static int vxlan_rcv(struct sock *sk, struct sk_buff *skb) ...@@ -1731,6 +1731,14 @@ static int vxlan_rcv(struct sock *sk, struct sk_buff *skb)
goto drop; goto drop;
} }
rcu_read_lock();
if (unlikely(!(vxlan->dev->flags & IFF_UP))) {
rcu_read_unlock();
atomic_long_inc(&vxlan->dev->rx_dropped);
goto drop;
}
stats = this_cpu_ptr(vxlan->dev->tstats); stats = this_cpu_ptr(vxlan->dev->tstats);
u64_stats_update_begin(&stats->syncp); u64_stats_update_begin(&stats->syncp);
stats->rx_packets++; stats->rx_packets++;
...@@ -1738,6 +1746,9 @@ static int vxlan_rcv(struct sock *sk, struct sk_buff *skb) ...@@ -1738,6 +1746,9 @@ static int vxlan_rcv(struct sock *sk, struct sk_buff *skb)
u64_stats_update_end(&stats->syncp); u64_stats_update_end(&stats->syncp);
gro_cells_receive(&vxlan->gro_cells, skb); gro_cells_receive(&vxlan->gro_cells, skb);
rcu_read_unlock();
return 0; return 0;
drop: drop:
......
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