It might be possible that 2 threads access the same data in the same
rcu grace period. The first thread calls call_rcu() to decrement the
refcount and free the data while the second thread increases the
refcount to use the data. To avoid this race condition all refcount
operations have to be atomic.
Reported-by: Sven Eckelmann <sven@narfation.org>
Signed-off-by: Marek Lindner <lindner_marek@yahoo.de>
It might be possible that 2 threads access the same data in the same
rcu grace period. The first thread calls call_rcu() to decrement the
refcount and free the data while the second thread increases the
refcount to use the data. To avoid this race condition all refcount
operations have to be atomic.
Reported-by: Sven Eckelmann <sven@narfation.org>
Signed-off-by: Marek Lindner <lindner_marek@yahoo.de>
The batman-adv vis server has to a stack which stores all information
about packets which should be send later. This stack is protected
with a spinlock that is used to prevent concurrent write access to it.
The send_vis_packets function has to take all elements from the stack
and send them to other hosts over the primary interface. The send will
be initiated without the lock which protects the stack.
The implementation using list_for_each_entry_safe has the problem that
it stores the next element as "safe ptr" to allow the deletion of the
current element in the list. The list may be modified during the
unlock/lock pair in the loop body which may make the safe pointer
not pointing to correct next element.
It is safer to remove and use the first element from the stack until no
elements are available. This does not need reduntant information which
would have to be validated each time the lock was removed.
Reported-by: Russell Senior <russell@personaltelco.net>
Signed-off-by: Sven Eckelmann <sven@narfation.org>
The free_info function will be called when no reference to the info
object exists anymore. It must be ensured that the allocated memory
gets freed and not only the elements which are managed by the info
object.
Signed-off-by: Sven Eckelmann <sven@narfation.org>
A newly created vis info object must be removed when it couldn't be
added to the hash. The old_info which has to be replaced was already
removed and isn't related to the hash anymore.
Signed-off-by: Sven Eckelmann <sven@narfation.org>
The hash_iterate removal introduced a bug leading to a kernel panic when
fetching the vis data on a vis server. That commit forgot to rename one
variable name, which this commit fixes now.
Reported-by: Russell Senior <russell@personaltelco.net>
Signed-off-by: Linus Lüssing <linus.luessing@web.de>
Signed-off-by: Sven Eckelmann <sven@narfation.org>
B.A.T.M.A.N. (better approach to mobile ad-hoc networking) is a routing
protocol for multi-hop ad-hoc mesh networks. The networks may be wired or
wireless. See http://www.open-mesh.org/ for more information and user space
tools.
Signed-off-by: Sven Eckelmann <sven@narfation.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Marek Lindner
David S. Miller
Sven Eckelmann
Linus Lüssing