Patchwork [v2,1/5] pktgen: fix crash when generating IPv6 packets

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Submitter Amerigo Wang
Date Oct. 10, 2012, 3:48 a.m.
Message ID <1349840900-24138-1-git-send-email-amwang@redhat.com>
Download mbox | patch
Permalink /patch/190541/
State Accepted
Delegated to: David Miller
Headers show

Comments

Amerigo Wang - Oct. 10, 2012, 3:48 a.m.
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: <stable@vger.kernel.org>
Cc: David S. Miller <davem@davemloft.net>
Signed-off-by: Cong Wang <amwang@redhat.com>
---
 net/core/pktgen.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
David Miller - Oct. 11, 2012, 2:33 a.m.
From: Cong Wang <amwang@redhat.com>
Date: Wed, 10 Oct 2012 11:48:16 +0800

> 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: <stable@vger.kernel.org>
> Cc: David S. Miller <davem@davemloft.net>
> Signed-off-by: Cong Wang <amwang@redhat.com>

Applied.
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Patch

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);
 	}