From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.linuxfoundation.org ([140.211.169.12]:42536 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S934905AbeCGTmp (ORCPT ); Wed, 7 Mar 2018 14:42:45 -0500 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Ursula Braun , Julian Wiedmann , "David S. Miller" Subject: [PATCH 4.15 088/122] s390/qeth: fix underestimated count of buffer elements Date: Wed, 7 Mar 2018 11:38:20 -0800 Message-Id: <20180307191742.109099514@linuxfoundation.org> In-Reply-To: <20180307191729.190879024@linuxfoundation.org> References: <20180307191729.190879024@linuxfoundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: stable-owner@vger.kernel.org List-ID: 4.15-stable review patch. If anyone has any objections, please let me know. ------------------ From: Ursula Braun [ Upstream commit 89271c65edd599207dd982007900506283c90ae3 ] For a memory range/skb where the last byte falls onto a page boundary (ie. 'end' is of the form xxx...xxx001), the PFN_UP() part of the calculation currently doesn't round up to the next PFN due to an off-by-one error. Thus qeth believes that the skb occupies one page less than it actually does, and may select a IO buffer that doesn't have enough spare buffer elements to fit all of the skb's data. HW detects this as a malformed buffer descriptor, and raises an exception which then triggers device recovery. Fixes: 2863c61334aa ("qeth: refactor calculation of SBALE count") Signed-off-by: Ursula Braun Signed-off-by: Julian Wiedmann Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- drivers/s390/net/qeth_core.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/drivers/s390/net/qeth_core.h +++ b/drivers/s390/net/qeth_core.h @@ -836,7 +836,7 @@ struct qeth_trap_id { */ static inline int qeth_get_elements_for_range(addr_t start, addr_t end) { - return PFN_UP(end - 1) - PFN_DOWN(start); + return PFN_UP(end) - PFN_DOWN(start); } static inline int qeth_get_micros(void)