[SCTP]: Always linearise packet on input
I was looking at a RHEL5 bug report involving Xen and SCTP
(https://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=212550).
It turns out that SCTP wasn't written to handle skb fragments at
all. The absence of any calls to skb_may_pull is testament to
that.
It just so happens that Xen creates fragmented packets more often
than other scenarios (header & data split when going from domU to
dom0). That's what caused this bug to show up.
Until someone has the time sits down and audits the entire net/sctp
directory, here is a conservative and safe solution that simply
linearises all packets on input.
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/sctp/input.c b/net/sctp/input.c
index 64f6301..99c0501 100644
--- a/net/sctp/input.c
+++ b/net/sctp/input.c
@@ -135,6 +135,9 @@
SCTP_INC_STATS_BH(SCTP_MIB_INSCTPPACKS);
+ if (skb_linearize(skb))
+ goto discard_it;
+
sh = (struct sctphdr *) skb->h.raw;
/* Pull up the IP and SCTP headers. */