Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S965164Ab1C3V3G (ORCPT ); Wed, 30 Mar 2011 17:29:06 -0400 Received: from mga03.intel.com ([143.182.124.21]:56389 "EHLO mga03.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933624Ab1C3VJD (ORCPT ); Wed, 30 Mar 2011 17:09:03 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.63,270,1299484800"; d="scan'208";a="411278573" From: Andi Kleen References: <20110330203.501921634@firstfloor.org> In-Reply-To: <20110330203.501921634@firstfloor.org> To: sean.hefty@intel.com, dledford@redhat.com, roland@purestorage.com, gregkh@suse.de, ak@linux.intel.com, linux-kernel@vger.kernel.org, stable@kernel.org, tim.bird@am.sony.com Subject: [PATCH] [196/275] IB/cm: Bump reference count on cm_id before invoking callback Message-Id: <20110330210720.182FB3E1A05@tassilo.jf.intel.com> Date: Wed, 30 Mar 2011 14:07:20 -0700 (PDT) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1938 Lines: 48 2.6.35-longterm review patch. If anyone has any objections, please let me 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 Signed-off-by: Andi Kleen --- drivers/infiniband/core/cm.c | 1 + 1 file changed, 1 insertion(+) Index: linux-2.6.35.y/drivers/infiniband/core/cm.c =================================================================== --- linux-2.6.35.y.orig/drivers/infiniband/core/cm.c 2011-03-29 22:50:42.296176166 -0700 +++ linux-2.6.35.y/drivers/infiniband/core/cm.c 2011-03-29 23:03:02.367239599 -0700 @@ -2987,6 +2987,7 @@ 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; -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/