From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755271Ab1CVAAT (ORCPT ); Mon, 21 Mar 2011 20:00:19 -0400 Received: from kroah.org ([198.145.64.141]:48992 "EHLO coco.kroah.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754945Ab1CUXNm (ORCPT ); Mon, 21 Mar 2011 19:13:42 -0400 X-Mailbox-Line: From gregkh@clark.kroah.org Mon Mar 21 16:10:52 2011 Message-Id: <20110321231052.198549685@clark.kroah.org> User-Agent: quilt/0.48-16.4 Date: Mon, 21 Mar 2011 16:09:54 -0700 From: Greg KH To: linux-kernel@vger.kernel.org, stable@kernel.org Cc: stable-review@kernel.org, torvalds@linux-foundation.org, akpm@linux-foundation.org, alan@lxorguk.ukuu.org.uk, Sean Hefty , Doug Ledford , Roland Dreier Subject: [14/44] IB/cm: Bump reference count on cm_id before invoking callback In-Reply-To: <20110321231105.GA1744@kroah.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 2.6.32-longterm review patch. If anyone has any objections, please let us know. ------------------ From: Sean Hefty 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 Acked-by: Doug Ledford Signed-off-by: Roland Dreier Signed-off-by: Greg Kroah-Hartman --- drivers/infiniband/core/cm.c | 1 + 1 file changed, 1 insertion(+) --- a/drivers/infiniband/core/cm.c +++ b/drivers/infiniband/core/cm.c @@ -2986,6 +2986,7 @@ 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;