From patchwork Tue Oct 9 10:05:27 2012 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Subject: [1/5] pktgen: fix crash when generating IPv6 packets Date: Tue, 09 Oct 2012 00:05:27 -0000 From: Amerigo Wang X-Patchwork-Id: 190254 Message-Id: <1349777131-4425-1-git-send-email-amwang@redhat.com> To: netdev@vger.kernel.org Cc: Cong Wang , , "David S. Miller" 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); }