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| author | Subash Abhinov Kasiviswanathan <subashab@codeaurora.org> | 2019-09-10 23:02:57 +0300 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2019-09-12 13:55:34 +0300 |
| commit | 10cc514f451a0f239aa34f91bc9dc954a9397840 (patch) | |
| tree | d0f714afc565abac165983c4870e62b6beda2f3d /net/core | |
| parent | d23dbc479a8e813db4161a695d67da0e36557846 (diff) | |
| download | linux-10cc514f451a0f239aa34f91bc9dc954a9397840.tar.xz | |
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>
Diffstat (limited to 'net/core')
| -rw-r--r-- | net/core/dev.c | 2 |
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) { rollback_registered(dev); + rcu_barrier(); + dev->reg_state = NETREG_UNREGISTERED; } /* |