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116a1b9f1c
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: 9a41e38a46 ("IB/mad: Use IDR for agent IDs")
Link: https://lore.kernel.org/r/20200621104738.54850-2-leon@kernel.org
Signed-off-by: Shay Drory <shayd@mellanox.com>
Reviewed-by: Maor Gottlieb <maorg@mellanox.com>
Signed-off-by: Leon Romanovsky <leonro@mellanox.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.