From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755391AbbHEWMD (ORCPT ); Wed, 5 Aug 2015 18:12:03 -0400 Received: from youngberry.canonical.com ([91.189.89.112]:38490 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754408AbbHEVuM (ORCPT ); Wed, 5 Aug 2015 17:50:12 -0400 From: Kamal Mostafa To: linux-kernel@vger.kernel.org, stable@vger.kernel.org, kernel-team@lists.ubuntu.com Cc: Daniel Axtens , Michael Ellerman , Kamal Mostafa Subject: [PATCH 3.19.y-ckt 040/107] cxl: Check if afu is not null in cxl_slbia Date: Wed, 5 Aug 2015 14:48:32 -0700 Message-Id: <1438811379-384-41-git-send-email-kamal@canonical.com> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1438811379-384-1-git-send-email-kamal@canonical.com> References: <1438811379-384-1-git-send-email-kamal@canonical.com> X-Extended-Stable: 3.19 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.19.8-ckt5 -stable review patch. If anyone has any objections, please let me know. ------------------ From: Daniel Axtens commit 2c069a118fe1d80c47dca84e1561045fc7f3cc9e upstream. The pointer to an AFU in the adapter's list of AFUs can be null if we're in the process of removing AFUs. The afu_list_lock doesn't guard against this. Say we have 2 slices, and we're in the process of removing cxl. - We remove the AFUs in order (see cxl_remove). In cxl_remove_afu for AFU 0, we take the lock, set adapter->afu[0] = NULL, and release the lock. - Then we get an slbia. In cxl_slbia we take the lock, and set afu = adapter->afu[0], which is NULL. - Therefore our attempt to check afu->enabled will blow up. Therefore, check if afu is a null pointer before dereferencing it. Signed-off-by: Daniel Axtens Acked-by: Michael Neuling Acked-by: Ian Munsie Signed-off-by: Michael Ellerman Signed-off-by: Kamal Mostafa --- drivers/misc/cxl/main.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/misc/cxl/main.c b/drivers/misc/cxl/main.c index 4cde9b6..619c7b4 100644 --- a/drivers/misc/cxl/main.c +++ b/drivers/misc/cxl/main.c @@ -71,7 +71,7 @@ static inline void cxl_slbia_core(struct mm_struct *mm) spin_lock(&adapter->afu_list_lock); for (slice = 0; slice < adapter->slices; slice++) { afu = adapter->afu[slice]; - if (!afu->enabled) + if (!afu || !afu->enabled) continue; rcu_read_lock(); idr_for_each_entry(&afu->contexts_idr, ctx, id) -- 1.9.1