| Message ID | 20190310173640.54607-1-edumazet@google.com |
|---|---|
| State | Accepted |
| Delegated to: | David Miller |
| Headers | show |
| Series | [net] vxlan: test dev->flags & IFF_UP before calling gro_cells_receive() | expand |
From: Eric Dumazet <edumazet@google.com> Date: Sun, 10 Mar 2019 10:36:40 -0700 > 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 <edumazet@google.com> Applied and queued up for -stable, thanks Eric.
diff --git a/drivers/net/vxlan.c b/drivers/net/vxlan.c index a3c46d78d216bf088545d7550170545c1771ab79..3d716790ebee4fc0bb3975c1720025688a109bbb 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:
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 <edumazet@google.com> --- drivers/net/vxlan.c | 11 +++++++++++ 1 file changed, 11 insertions(+)