tipc: fix race in disc create/delete
authorYing Xue <ying.xue@windriver.com>
Mon, 21 Apr 2014 02:55:52 +0000 (10:55 +0800)
committerDavid S. Miller <davem@davemloft.net>
Wed, 23 Apr 2014 01:17:53 +0000 (21:17 -0400)
commita8b9b96e959f3c035af20b1bd2ba67b0b7269b19
tree02d52832745176ee6d63579f50d375caddd1fc62
parent28dd94187afd660a350d01d6bad4a915a6d570b8
tipc: fix race in disc create/delete

Commit a21a584d6720ce349b05795b9bcfab3de8e58419 (tipc: fix neighbor
detection problem after hw address change) introduces a race condition
involving tipc_disc_delete() and tipc_disc_add/remove_dest that can
cause TIPC to dereference the pointer to the bearer discovery request
structure after it has been freed since a stray pointer is left in the
bearer structure.

In order to fix the issue, the process of resetting the discovery
request handler is optimized: the discovery request handler and request
buffer are just reset instead of being freed, allocated and initialized.
As the request point is always valid and the request's lock is taken
while the request handler is reset, the race doesn't happen any more.

Reported-by: Erik Hugne <erik.hugne@ericsson.com>
Signed-off-by: Ying Xue <ying.xue@windriver.com>
Reviewed-by: Erik Hugne <erik.hugne@ericsson.com>
Tested-by: Erik Hugne <erik.hugne@ericsson.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
net/tipc/bearer.c
net/tipc/discover.c
net/tipc/discover.h