From 59cbf56fcd98ba2a715b6e97c4e43f773f956393 Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Sun, 10 Mar 2019 10:36:40 -0700 Subject: vxlan: test dev->flags & IFF_UP before calling gro_cells_receive() Same reasons than the ones explained in commit 4179cb5a4c92 ("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: d342894c5d2f ("vxlan: virtual extensible lan") Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller --- drivers/net/vxlan.c | 11 +++++++++++ 1 file changed, 11 insertions(+) (limited to 'drivers/net/vxlan.c') diff --git a/drivers/net/vxlan.c b/drivers/net/vxlan.c index 7610c51b33a0..077f1b9f2761 100644 --- a/drivers/net/vxlan.c +++ b/drivers/net/vxlan.c @@ -1731,6 +1731,14 @@ 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++; @@ -1738,6 +1746,9 @@ 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: -- cgit v1.2.3-59-g8ed1b