From ac43c058283e037c5acdee95ada41075e0e2dde5 Mon Sep 17 00:00:00 2001 From: Amerigo Wang Date: Tue, 9 Oct 2012 17:48:16 +0000 Subject: [PATCH] pktgen: fix crash when generating IPv6 packets commit 5aa8b572007c4bca1e6d3dd4c4820f1ae49d6bb2 upstream. 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. Signed-off-by: Cong Wang Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- net/core/pktgen.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/net/core/pktgen.c b/net/core/pktgen.c index 148e73d2c451..e356b8d52bad 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); } -- 2.39.5