From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933648AbcJ0D6w (ORCPT ); Wed, 26 Oct 2016 23:58:52 -0400 Received: from szxga01-in.huawei.com ([58.251.152.64]:64916 "EHLO szxga01-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932464AbcJ0D6u (ORCPT ); Wed, 26 Oct 2016 23:58:50 -0400 From: zhongjiang To: , , , , , , CC: , Subject: [PATCH] net: avoid uninitialized variable Date: Thu, 27 Oct 2016 11:56:09 +0800 Message-ID: <1477540569-12199-1-git-send-email-zhongjiang@huawei.com> X-Mailer: git-send-email 1.7.12.4 MIME-Version: 1.0 Content-Type: text/plain X-Originating-IP: [10.175.102.37] X-CFilter-Loop: Reflected Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: zhong jiang when I compiler the newest kernel, I hit the following error with Werror=may-uninitalized. net/core/flow_dissector.c: In function ?._skb_flow_dissect? include/uapi/linux/swab.h:100:46: error: ?.lan?.may be used uninitialized in this function [-Werror=maybe-uninitialized] net/core/flow_dissector.c:248:26: note: ?.lan?.was declared here This adds an additional check for proto to explicitly tell the compiler that vlan pointer have the correct value before it is used. Signed-off-by: zhong jiang --- net/core/flow_dissector.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/net/core/flow_dissector.c b/net/core/flow_dissector.c index 1a7b80f..a04d9cf 100644 --- a/net/core/flow_dissector.c +++ b/net/core/flow_dissector.c @@ -245,7 +245,7 @@ bool __skb_flow_dissect(const struct sk_buff *skb, } case htons(ETH_P_8021AD): case htons(ETH_P_8021Q): { - const struct vlan_hdr *vlan; + const struct vlan_hdr *vlan = NULL; if (skb_vlan_tag_present(skb)) proto = skb->protocol; @@ -276,7 +276,8 @@ bool __skb_flow_dissect(const struct sk_buff *skb, key_vlan->vlan_id = skb_vlan_tag_get_id(skb); key_vlan->vlan_priority = (skb_vlan_tag_get_prio(skb) >> VLAN_PRIO_SHIFT); - } else { + } else if (proto == cpu_to_be16(ETH_P_8021Q) || + proto == cpu_to_be16(ETH_P_8021AD)) { key_vlan->vlan_id = ntohs(vlan->h_vlan_TCI) & VLAN_VID_MASK; key_vlan->vlan_priority = -- 1.8.3.1