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| author | Vladimir Oltean <vladimir.oltean@nxp.com> | 2020-09-22 01:07:09 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2020-09-26 18:03:12 +0200 |
| commit | 450c0c00a5b01ee474454c5923fbe47a462bd6f8 (patch) | |
| tree | 7702e030c39c16ef141cdc94261acf9ef1f483ae /net/bridge | |
| parent | d0b05f019f843c64dda1347fc3e6459e0e7b7f8f (diff) | |
net: bridge: br_vlan_get_pvid_rcu() should dereference the VLAN group under RCU
[ Upstream commit 99f62a746066fa436aa15d4606a538569540db08 ]
When calling the RCU brother of br_vlan_get_pvid(), lockdep warns:
=============================
WARNING: suspicious RCU usage
5.9.0-rc3-01631-g13c17acb8e38-dirty #814 Not tainted
-----------------------------
net/bridge/br_private.h:1054 suspicious rcu_dereference_protected() usage!
Call trace:
lockdep_rcu_suspicious+0xd4/0xf8
__br_vlan_get_pvid+0xc0/0x100
br_vlan_get_pvid_rcu+0x78/0x108
The warning is because br_vlan_get_pvid_rcu() calls nbp_vlan_group()
which calls rtnl_dereference() instead of rcu_dereference(). In turn,
rtnl_dereference() calls rcu_dereference_protected() which assumes
operation under an RCU write-side critical section, which obviously is
not the case here. So, when the incorrect primitive is used to access
the RCU-protected VLAN group pointer, READ_ONCE() is not used, which may
cause various unexpected problems.
I'm sad to say that br_vlan_get_pvid() and br_vlan_get_pvid_rcu() cannot
share the same implementation. So fix the bug by splitting the 2
functions, and making br_vlan_get_pvid_rcu() retrieve the VLAN groups
under proper locking annotations.
Fixes: 7582f5b70f9a ("bridge: add br_vlan_get_pvid_rcu()")
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'net/bridge')
| -rw-r--r-- | net/bridge/br_vlan.c | 27 |
1 files changed, 17 insertions, 10 deletions
diff --git a/net/bridge/br_vlan.c b/net/bridge/br_vlan.c index bb98984cd27d..48413b5eb61f 100644 --- a/net/bridge/br_vlan.c +++ b/net/bridge/br_vlan.c @@ -1229,11 +1229,13 @@ void br_vlan_get_stats(const struct net_bridge_vlan *v, } } -static int __br_vlan_get_pvid(const struct net_device *dev, - struct net_bridge_port *p, u16 *p_pvid) +int br_vlan_get_pvid(const struct net_device *dev, u16 *p_pvid) { struct net_bridge_vlan_group *vg; + struct net_bridge_port *p; + ASSERT_RTNL(); + p = br_port_get_check_rtnl(dev); if (p) vg = nbp_vlan_group(p); else if (netif_is_bridge_master(dev)) @@ -1244,18 +1246,23 @@ static int __br_vlan_get_pvid(const struct net_device *dev, *p_pvid = br_get_pvid(vg); return 0; } - -int br_vlan_get_pvid(const struct net_device *dev, u16 *p_pvid) -{ - ASSERT_RTNL(); - - return __br_vlan_get_pvid(dev, br_port_get_check_rtnl(dev), p_pvid); -} EXPORT_SYMBOL_GPL(br_vlan_get_pvid); int br_vlan_get_pvid_rcu(const struct net_device *dev, u16 *p_pvid) { - return __br_vlan_get_pvid(dev, br_port_get_check_rcu(dev), p_pvid); + struct net_bridge_vlan_group *vg; + struct net_bridge_port *p; + + p = br_port_get_check_rcu(dev); + if (p) + vg = nbp_vlan_group_rcu(p); + else if (netif_is_bridge_master(dev)) + vg = br_vlan_group_rcu(netdev_priv(dev)); + else + return -EINVAL; + + *p_pvid = br_get_pvid(vg); + return 0; } EXPORT_SYMBOL_GPL(br_vlan_get_pvid_rcu); |