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

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[ Upstream commit 59cbf56fcd ]

Same reasons than the ones explained in commit 4179cb5a4c
("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: d342894c5d ("vxlan: virtual extensible lan")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Eric Dumazet
2019-03-10 10:36:40 -07:00
committed by Greg Kroah-Hartman
parent 9f7aeee654
commit f09a656b68
1 changed files with 11 additions and 0 deletions
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11
drivers/net/vxlan.c
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@@ -1469,6 +1469,14 @@ static int vxlan_rcv(struct sock *sk, struct sk_buff *skb)
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);
u64_stats_update_begin(&stats->syncp);
stats->rx_packets++;
@@ -1476,6 +1484,9 @@ static int vxlan_rcv(struct sock *sk, struct sk_buff *skb)
u64_stats_update_end(&stats->syncp);
gro_cells_receive(&vxlan->gro_cells, skb);
rcu_read_unlock();
return 0;
drop: