tree d02ab5f3e77affd68cf7a6d40a728376b94d47db
parent 5841c1bb484f550063ae82040e90e6d42c66b73d
author Sven Eckelmann <sven@narfation.org> 1584397864 +0100
committer Greg Kroah-Hartman <gregkh@linuxfoundation.org> 1584691675 +0100

batman-adv: Avoid free/alloc race when handling OGM buffer

commit 40e220b4218bb3d278e5e8cc04ccdfd1c7ff8307 upstream.

Each slave interface of an B.A.T.M.A.N. IV virtual interface has an OGM
packet buffer which is initialized using data from netdevice notifier and
other rtnetlink related hooks. It is sent regularly via various slave
interfaces of the batadv virtual interface and in this process also
modified (realloced) to integrate additional state information via TVLV
containers.

It must be avoided that the worker item is executed without a common lock
with the netdevice notifier/rtnetlink helpers. Otherwise it can either
happen that half modified/freed data is sent out or functions modifying the
OGM buffer try to access already freed memory regions.

Reported-by: syzbot+0cc629f19ccb8534935b@syzkaller.appspotmail.com
Fixes: c6c8fea29769 ("net: Add batman-adv meshing protocol")
Signed-off-by: Sven Eckelmann <sven@narfation.org>
Signed-off-by: Simon Wunderlich <sw@simonwunderlich.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>