From mboxrd@z Thu Jan 1 00:00:00 1970 From: Cong Wang Subject: [Patch v2 1/5] pktgen: fix crash when generating IPv6 packets Date: Wed, 10 Oct 2012 11:48:16 +0800 Message-ID: <1349840900-24138-1-git-send-email-amwang@redhat.com> Cc: Cong Wang , , "David S. Miller" To: netdev@vger.kernel.org Return-path: Received: from mx1.redhat.com ([209.132.183.28]:12107 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754618Ab2JJDs3 (ORCPT ); Tue, 9 Oct 2012 23:48:29 -0400 Sender: netdev-owner@vger.kernel.org List-ID: For IPv6, sizeof(struct ipv6hdr) = 40, thus the following expression will result negative: datalen = pkt_dev->cur_pkt_size - 14 - sizeof(struct ipv6hdr) - sizeof(struct udphdr) - pkt_dev->pkt_overhead; And, the check "if (datalen < sizeof(struct pktgen_hdr))" will be passed as "datalen" is promoted to unsigned, therefore will cause a crash later. This is a quick fix by checking if "datalen" is negative. The following patch will increase the default value of 'min_pkt_size' for IPv6. This bug should exist for a long time, so Cc -stable too. Cc: Cc: David S. Miller Signed-off-by: Cong Wang --- net/core/pktgen.c | 2 +- 1 files changed, 1 insertions(+), 1 deletions(-) diff --git a/net/core/pktgen.c b/net/core/pktgen.c index 148e73d..e356b8d 100644 --- a/net/core/pktgen.c +++ b/net/core/pktgen.c @@ -2927,7 +2927,7 @@ static struct sk_buff *fill_packet_ipv6(struct net_device *odev, sizeof(struct ipv6hdr) - sizeof(struct udphdr) - pkt_dev->pkt_overhead; - if (datalen < sizeof(struct pktgen_hdr)) { + if (datalen < 0 || datalen < sizeof(struct pktgen_hdr)) { datalen = sizeof(struct pktgen_hdr); net_info_ratelimited("increased datalen to %d\n", datalen); } -- 1.7.7.6