This is a note to let you know that I've just added the patch titled
IB/mad: Fix use after free when destroying MAD agent
to the 4.19-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
ib-mad-fix-use-after-free-when-destroying-mad-agent.patch
and it can be found in the queue-4.19 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit a0a00dc6afcd7429de3b9d8d8b67a01a28d21ec1
Author: Shay Drory <shayd@xxxxxxxxxxxx>
Date: Sun Jun 21 13:47:35 2020 +0300
IB/mad: Fix use after free when destroying MAD agent
[ Upstream commit 116a1b9f1cb769b83e5adff323f977a62b1dcb2e ]
Currently, when RMPP MADs are processed while the MAD agent is destroyed,
it could result in use after free of rmpp_recv, as decribed below:
cpu-0 cpu-1
----- -----
ib_mad_recv_done()
ib_mad_complete_recv()
ib_process_rmpp_recv_wc()
unregister_mad_agent()
ib_cancel_rmpp_recvs()
cancel_delayed_work()
process_rmpp_data()
start_rmpp()
queue_delayed_work(rmpp_recv->cleanup_work)
destroy_rmpp_recv()
free_rmpp_recv()
cleanup_work()[1]
spin_lock_irqsave(&rmpp_recv->agent->lock) <-- use after free
[1] cleanup_work() == recv_cleanup_handler
Fix it by waiting for the MAD agent reference count becoming zero before
calling to ib_cancel_rmpp_recvs().
Fixes: 9a41e38a467c ("IB/mad: Use IDR for agent IDs")
Link: https://lore.kernel.org/r/20200621104738.54850-2-leon@xxxxxxxxxx
Signed-off-by: Shay Drory <shayd@xxxxxxxxxxxx>
Reviewed-by: Maor Gottlieb <maorg@xxxxxxxxxxxx>
Signed-off-by: Leon Romanovsky <leonro@xxxxxxxxxxxx>
Signed-off-by: Jason Gunthorpe <jgg@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/drivers/infiniband/core/mad.c b/drivers/infiniband/core/mad.c
index fd0a2fd8bfdf7..a36b3b4f5c0a2 100644
--- a/drivers/infiniband/core/mad.c
+++ b/drivers/infiniband/core/mad.c
@@ -615,10 +615,10 @@ static void unregister_mad_agent(struct ib_mad_agent_private *mad_agent_priv)
idr_unlock(&ib_mad_clients);
flush_workqueue(port_priv->wq);
- ib_cancel_rmpp_recvs(mad_agent_priv);
deref_mad_agent(mad_agent_priv);
wait_for_completion(&mad_agent_priv->comp);
+ ib_cancel_rmpp_recvs(mad_agent_priv);
ib_mad_agent_security_cleanup(&mad_agent_priv->agent);
