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authorSubash Abhinov Kasiviswanathan <subashab@codeaurora.org>2019-09-10 14:02:57 -0600
committerDavid S. Miller <davem@davemloft.net>2019-09-12 11:55:34 +0100
commit10cc514f451a0f239aa34f91bc9dc954a9397840 (patch)
parentd23dbc479a8e813db4161a695d67da0e36557846 (diff)
net: Fix null de-reference of device refcount
In event of failure during register_netdevice, free_netdev is invoked immediately. free_netdev assumes that all the netdevice refcounts have been dropped prior to it being called and as a result frees and clears out the refcount pointer. However, this is not necessarily true as some of the operations in the NETDEV_UNREGISTER notifier handlers queue RCU callbacks for invocation after a grace period. The IPv4 callback in_dev_rcu_put tries to access the refcount after free_netdev is called which leads to a null de-reference- 44837.761523: <6> Unable to handle kernel paging request at virtual address 0000004a88287000 44837.761651: <2> pc : in_dev_finish_destroy+0x4c/0xc8 44837.761654: <2> lr : in_dev_finish_destroy+0x2c/0xc8 44837.762393: <2> Call trace: 44837.762398: <2> in_dev_finish_destroy+0x4c/0xc8 44837.762404: <2> in_dev_rcu_put+0x24/0x30 44837.762412: <2> rcu_nocb_kthread+0x43c/0x468 44837.762418: <2> kthread+0x118/0x128 44837.762424: <2> ret_from_fork+0x10/0x1c Fix this by waiting for the completion of the call_rcu() in case of register_netdevice errors. Fixes: 93ee31f14f6f ("[NET]: Fix free_netdev on register_netdev failure.") Cc: Sean Tranchetti <stranche@codeaurora.org> Signed-off-by: Subash Abhinov Kasiviswanathan <subashab@codeaurora.org> Signed-off-by: David S. Miller <davem@davemloft.net>
1 files changed, 2 insertions, 0 deletions
diff --git a/net/core/dev.c b/net/core/dev.c
index 0891f499c1bb..5156c0edebe8 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -8758,6 +8758,8 @@ int register_netdevice(struct net_device *dev)
ret = notifier_to_errno(ret);
if (ret) {
+ rcu_barrier();
dev->reg_state = NETREG_UNREGISTERED;