84 lines
2.9 KiB
Diff
84 lines
2.9 KiB
Diff
Bugzilla: 1025770
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Upstream-status: 3.13 (commit 859828c0ea476b42f3a)
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From 1a62121ead27a218d4b02b7130a6f5f6ca9c247e Mon Sep 17 00:00:00 2001
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From: Jiri Pirko <jiri@resnulli.us>
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Date: Thu, 5 Dec 2013 16:27:37 +0100
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Subject: [PATCH] br: fix use of ->rx_handler_data in code executed on
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non-rx_handler path
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br_stp_rcv() is reached by non-rx_handler path. That means there is no
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guarantee that dev is bridge port and therefore simple NULL check of
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->rx_handler_data is not enough. There is need to check if dev is really
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bridge port and since only rcu read lock is held here, do it by checking
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->rx_handler pointer.
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Note that synchronize_net() in netdev_rx_handler_unregister() ensures
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this approach as valid.
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Introduced originally by:
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commit f350a0a87374418635689471606454abc7beaa3a
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"bridge: use rx_handler_data pointer to store net_bridge_port pointer"
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Fixed but not in the best way by:
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commit b5ed54e94d324f17c97852296d61a143f01b227a
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"bridge: fix RCU races with bridge port"
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Reintroduced by:
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commit 716ec052d2280d511e10e90ad54a86f5b5d4dcc2
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"bridge: fix NULL pointer deref of br_port_get_rcu"
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Please apply to stable trees as well. Thanks.
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RH bugzilla reference: https://bugzilla.redhat.com/show_bug.cgi?id=1025770
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Reported-by: Laine Stump <laine@redhat.com>
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Debugged-by: Michael S. Tsirkin <mst@redhat.com>
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Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
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Signed-off-by: Jiri Pirko <jiri@resnulli.us>
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Acked-by: Michael S. Tsirkin <mst@redhat.com>
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Acked-by: Eric Dumazet <edumazet@google.com>
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Signed-off-by: David S. Miller <davem@davemloft.net>
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---
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net/bridge/br_private.h | 10 ++++++++++
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net/bridge/br_stp_bpdu.c | 2 +-
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2 files changed, 11 insertions(+), 1 deletion(-)
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diff --git a/net/bridge/br_private.h b/net/bridge/br_private.h
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index e14c33b..9a63c42 100644
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--- a/net/bridge/br_private.h
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+++ b/net/bridge/br_private.h
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@@ -442,6 +442,16 @@ extern netdev_features_t br_features_recompute(struct net_bridge *br,
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extern int br_handle_frame_finish(struct sk_buff *skb);
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extern rx_handler_result_t br_handle_frame(struct sk_buff **pskb);
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+static inline bool br_rx_handler_check_rcu(const struct net_device *dev)
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+{
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+ return rcu_dereference(dev->rx_handler) == br_handle_frame;
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+}
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+
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+static inline struct net_bridge_port *br_port_get_check_rcu(const struct net_device *dev)
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+{
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+ return br_rx_handler_check_rcu(dev) ? br_port_get_rcu(dev) : NULL;
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+}
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+
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/* br_ioctl.c */
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extern int br_dev_ioctl(struct net_device *dev, struct ifreq *rq, int cmd);
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extern int br_ioctl_deviceless_stub(struct net *net, unsigned int cmd, void __user *arg);
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diff --git a/net/bridge/br_stp_bpdu.c b/net/bridge/br_stp_bpdu.c
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index 8660ea3..bdb459d 100644
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--- a/net/bridge/br_stp_bpdu.c
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+++ b/net/bridge/br_stp_bpdu.c
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@@ -153,7 +153,7 @@ void br_stp_rcv(const struct stp_proto *proto, struct sk_buff *skb,
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if (buf[0] != 0 || buf[1] != 0 || buf[2] != 0)
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goto err;
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- p = br_port_get_rcu(dev);
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+ p = br_port_get_check_rcu(dev);
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if (!p)
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goto err;
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--
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1.8.3.1
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