Commit 29963437 authored Feb 23, 2011 by Sean Hefty Committed by Roland Dreier Mar 15, 2011

IB/cm: Bump reference count on cm_id before invoking callback



When processing a SIDR REQ, the ib_cm allocates a new cm_id.  The
refcount of the cm_id is initialized to 1.  However, cm_process_work
will decrement the refcount after invoking all callbacks.  The result
is that the cm_id will end up with refcount set to 0 by the end of the
sidr req handler.

If a user tries to destroy the cm_id, the destruction will proceed,
under the incorrect assumption that no other threads are referencing
the cm_id.  This can lead to a crash when the cm callback thread tries
to access the cm_id.

This problem was noticed as part of a larger investigation with kernel
crashes in the rdma_cm when running on a real time OS.

Signed-off-by: Sean Hefty <sean.hefty@intel.com>
Acked-by: Doug Ledford <dledford@redhat.com>
Cc: <stable@kernel.org>
Signed-off-by: Roland Dreier <roland@purestorage.com>

parent 25ae21a1

drivers/infiniband/core/cm.c

+1 −0

Original line number	Diff line number	Diff line
		@@ -2989,6 +2989,7 @@ static int cm_sidr_req_handler(struct cm_work *work)
		goto out; /* No match. */
		}
		atomic_inc(&cur_cm_id_priv->refcount);
		atomic_inc(&cm_id_priv->refcount);
		spin_unlock_irq(&cm.lock);

		cm_id_priv->id.cm_handler = cur_cm_id_priv->id.cm_handler;