mISDN: fix use-after-free bugs in l1oip timer handlers
[ Upstream commit 2568a7e0832ee30b0a351016d03062ab4e0e0a3f ]
The l1oip_cleanup() traverses the l1oip_ilist and calls
release_card() to cleanup module and stack. However,
release_card() calls del_timer() to delete the timers
such as keep_tl and timeout_tl. If the timer handler is
running, the del_timer() will not stop it and result in
UAF bugs. One of the processes is shown below:
(cleanup routine) | (timer handler)
release_card() | l1oip_timeout()
... |
del_timer() | ...
... |
kfree(hc) //FREE |
| hc->timeout_on = 0 //USE
Fix by calling del_timer_sync() in release_card(), which
makes sure the timer handlers have finished before the
resources, such as l1oip and so on, have been deallocated.
What's more, the hc->workq and hc->socket_thread can kick
those timers right back in. We add a bool flag to show
if card is released. Then, check this flag in hc->workq
and hc->socket_thread.
Fixes: 3712b42d4b1b ("Add layer1 over IP support")
Signed-off-by: Duoming Zhou <duoming@zju.edu.cn>
Reviewed-by: Leon Romanovsky <leonro@nvidia.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
2 files changed