From patchwork Tue Jan 22 13:21:13 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Marc Kleine-Budde X-Patchwork-Id: 1029278 X-Patchwork-Delegate: davem@davemloft.net Return-Path: X-Original-To: patchwork-incoming-netdev@ozlabs.org Delivered-To: patchwork-incoming-netdev@ozlabs.org Authentication-Results: ozlabs.org; spf=none (mailfrom) smtp.mailfrom=vger.kernel.org (client-ip=209.132.180.67; helo=vger.kernel.org; envelope-from=netdev-owner@vger.kernel.org; receiver=) Authentication-Results: ozlabs.org; dmarc=none (p=none dis=none) header.from=pengutronix.de Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id 43kTZr0DKfz9s2P for ; Wed, 23 Jan 2019 00:21:24 +1100 (AEDT) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728465AbfAVNVW (ORCPT ); Tue, 22 Jan 2019 08:21:22 -0500 Received: from metis.ext.pengutronix.de ([85.220.165.71]:38981 "EHLO metis.ext.pengutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728339AbfAVNVV (ORCPT ); Tue, 22 Jan 2019 08:21:21 -0500 Received: from heimdall.vpn.pengutronix.de ([2001:67c:670:205:1d::14] helo=blackshift.org) by metis.ext.pengutronix.de with esmtp (Exim 4.89) (envelope-from ) id 1glvzT-0004Kz-PE; Tue, 22 Jan 2019 14:21:19 +0100 From: Marc Kleine-Budde To: netdev@vger.kernel.org Cc: davem@davemloft.net, linux-can@vger.kernel.org, kernel@pengutronix.de, Manfred Schlaegl , linux-stable , Marc Kleine-Budde Subject: [PATCH 1/4] can: dev: __can_get_echo_skb(): fix bogous check for non-existing skb by removing it Date: Tue, 22 Jan 2019 14:21:13 +0100 Message-Id: <20190122132116.7074-2-mkl@pengutronix.de> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20190122132116.7074-1-mkl@pengutronix.de> References: <20190122132116.7074-1-mkl@pengutronix.de> MIME-Version: 1.0 X-SA-Exim-Connect-IP: 2001:67c:670:205:1d::14 X-SA-Exim-Mail-From: mkl@pengutronix.de X-SA-Exim-Scanned: No (on metis.ext.pengutronix.de); SAEximRunCond expanded to false X-PTX-Original-Recipient: netdev@vger.kernel.org Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org From: Manfred Schlaegl This patch revert commit 7da11ba5c506 ("can: dev: __can_get_echo_skb(): print error message, if trying to echo non existing skb") After introduction of this change we encountered following new error message on various i.MX plattforms (flexcan): | flexcan 53fc8000.can can0: __can_get_echo_skb: BUG! Trying to echo non | existing skb: can_priv::echo_skb[0] The introduction of the message was a mistake because priv->echo_skb[idx] = NULL is a perfectly valid in following case: If CAN_RAW_LOOPBACK is disabled (setsockopt) in applications, the pkt_type of the tx skb's given to can_put_echo_skb is set to PACKET_LOOPBACK. In this case can_put_echo_skb will not set priv->echo_skb[idx]. It is therefore kept NULL. As additional argument for revert: The order of check and usage of idx was changed. idx is used to access an array element before checking it's boundaries. Signed-off-by: Manfred Schlaegl Fixes: 7da11ba5c506 ("can: dev: __can_get_echo_skb(): print error message, if trying to echo non existing skb") Cc: linux-stable Signed-off-by: Marc Kleine-Budde --- drivers/net/can/dev.c | 27 +++++++++++++-------------- 1 file changed, 13 insertions(+), 14 deletions(-) diff --git a/drivers/net/can/dev.c b/drivers/net/can/dev.c index 3b3f88ffab53..c05e4d50d43d 100644 --- a/drivers/net/can/dev.c +++ b/drivers/net/can/dev.c @@ -480,8 +480,6 @@ EXPORT_SYMBOL_GPL(can_put_echo_skb); struct sk_buff *__can_get_echo_skb(struct net_device *dev, unsigned int idx, u8 *len_ptr) { struct can_priv *priv = netdev_priv(dev); - struct sk_buff *skb = priv->echo_skb[idx]; - struct canfd_frame *cf; if (idx >= priv->echo_skb_max) { netdev_err(dev, "%s: BUG! Trying to access can_priv::echo_skb out of bounds (%u/max %u)\n", @@ -489,20 +487,21 @@ struct sk_buff *__can_get_echo_skb(struct net_device *dev, unsigned int idx, u8 return NULL; } - if (!skb) { - netdev_err(dev, "%s: BUG! Trying to echo non existing skb: can_priv::echo_skb[%u]\n", - __func__, idx); - return NULL; - } + if (priv->echo_skb[idx]) { + /* Using "struct canfd_frame::len" for the frame + * length is supported on both CAN and CANFD frames. + */ + struct sk_buff *skb = priv->echo_skb[idx]; + struct canfd_frame *cf = (struct canfd_frame *)skb->data; + u8 len = cf->len; - /* Using "struct canfd_frame::len" for the frame - * length is supported on both CAN and CANFD frames. - */ - cf = (struct canfd_frame *)skb->data; - *len_ptr = cf->len; - priv->echo_skb[idx] = NULL; + *len_ptr = len; + priv->echo_skb[idx] = NULL; - return skb; + return skb; + } + + return NULL; } /*