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Message-Id: <20110321230712.370561917@clark.kroah.org>
Date: Mon, 21 Mar 2011 16:06:30 -0700
From: Greg KH <gregkh@...e.de>
To: linux-kernel@...r.kernel.org, stable@...nel.org
Cc: stable-review@...nel.org, torvalds@...ux-foundation.org,
akpm@...ux-foundation.org, alan@...rguk.ukuu.org.uk,
Sean Hefty <sean.hefty@...el.com>,
Doug Ledford <dledford@...hat.com>,
Roland Dreier <roland@...estorage.com>
Subject: [31/87] IB/cm: Bump reference count on cm_id before invoking callback
2.6.37-stable review patch. If anyone has any objections, please let us know.
------------------
From: Sean Hefty <sean.hefty@...el.com>
commit 29963437a48475036353b95ab142bf199adb909e upstream.
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@...el.com>
Acked-by: Doug Ledford <dledford@...hat.com>
Signed-off-by: Roland Dreier <roland@...estorage.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...e.de>
---
drivers/infiniband/core/cm.c | 1 +
1 file changed, 1 insertion(+)
--- a/drivers/infiniband/core/cm.c
+++ b/drivers/infiniband/core/cm.c
@@ -2989,6 +2989,7 @@ static int cm_sidr_req_handler(struct cm
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;
--
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