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When creating a cm_id during REQ the id immediately becomes visible to the
other MAD handlers, and shortly after the state is moved to IB_CM_REQ_RCVD
This allows cm_rej_handler() to run concurrently and free the work:
CPU 0 CPU1
cm_req_handler()
ib_create_cm_id()
cm_match_req()
id_priv->state = IB_CM_REQ_RCVD
cm_rej_handler()
cm_acquire_id()
spin_lock(&id_priv->lock)
switch (id_priv->state)
case IB_CM_REQ_RCVD:
cm_reset_to_idle()
kfree(id_priv->timewait_info);
goto destroy
destroy:
kfree(id_priv->timewait_info);
id_priv->timewait_info = NULL
Causing a double free or worse.
Do not free the timewait_info without also holding the
id_priv->lock. Simplify this entire flow by making the free unconditional
during cm_destroy_id() and removing the confusing special case error
unwind during creation of the timewait_info.
This also fixes a leak of the timewait if cm_destroy_id() is called in
IB_CM_ESTABLISHED with an XRC TGT QP. The state machine will be left in
ESTABLISHED while it needed to transition through IB_CM_TIMEWAIT to
release the timewait pointer.
Also fix a leak of the timewait_info if the caller mis-uses the API and
does ib_send_cm_reqs().
Fixes: a977049dac ("[PATCH] IB: Add the kernel CM implementation")
Link: https://lore.kernel.org/r/20200310092545.251365-4-leon@kernel.org
Signed-off-by: Leon Romanovsky <leonro@mellanox.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.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.