From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932705Ab1DYUqY (ORCPT ); Mon, 25 Apr 2011 16:46:24 -0400 Received: from 1wt.eu ([62.212.114.60]:34311 "EHLO 1wt.eu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932257Ab1DYUYq (ORCPT ); Mon, 25 Apr 2011 16:24:46 -0400 Message-Id: <20110425200236.818872291@pcw.home.local> User-Agent: quilt/0.48-1 Date: Mon, 25 Apr 2011 22:04:00 +0200 From: Willy Tarreau To: linux-kernel@vger.kernel.org, stable@kernel.org, stable-review@kernel.org Cc: Sean Hefty , Doug Ledford , Roland Dreier , Greg Kroah-Hartman Subject: [PATCH 088/173] IB/cm: Bump reference count on cm_id before invoking callback In-Reply-To: <46075c3a3ef08be6d70339617d6afc98@local> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 2.6.27.59-stable 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;