Re: [netfilter-core] Re: [lockup] 2.6.17-rc3: netfilter/sctp: lockup in sctp_new(), do_basic_checks()

[Patrick McHardy <kaber@trash.net>]

Ingo Molnar wrote:
>>
>>I just came up with a similar fix :) I think I'm going to take my own 
>>patch though because its IMO slightly nicer. Thanks anyway.
> 
> 
> could you send your patch so that i can start using it instead of mine?

I did a couple of minutes ago. Here it is again in case my last mail
won't show up.

[NETFILTER]: Fix endless loop in SCTP conntrack

When a chunk length is zero, for_each_sctp_chunk() doesn't make any forward
progress and loops forever. A chunk length of 0 is invalid, so just abort
in that case.

Reported by Ingo Molnar <mingo@elte.hu>.

Signed-off-by: Patrick McHardy <kaber@trash.net>

---
commit 32491b3d62bc8c3ff2400deebd46972ebc7332af
tree 7249133ec32c18f4e6f989560e8d86b5e2e2cf0c
parent 462f3ddd384045c731b3268a1b9c91c834a5a68a
author Patrick McHardy <kaber@trash.net> Tue, 02 May 2006 15:44:30 +0200
committer Patrick McHardy <kaber@trash.net> Tue, 02 May 2006 15:44:30 +0200

 net/ipv4/netfilter/ip_conntrack_proto_sctp.c |    4 ++--
 net/netfilter/nf_conntrack_proto_sctp.c      |    4 ++--
 2 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/net/ipv4/netfilter/ip_conntrack_proto_sctp.c b/net/ipv4/netfilter/ip_conntrack_proto_sctp.c
index 5259abd..ebd4ecf 100644
--- a/net/ipv4/netfilter/ip_conntrack_proto_sctp.c
+++ b/net/ipv4/netfilter/ip_conntrack_proto_sctp.c
@@ -209,8 +209,8 @@ static int sctp_print_conntrack(struct s
 #define for_each_sctp_chunk(skb, sch, _sch, offset, count)		\
 for (offset = skb->nh.iph->ihl * 4 + sizeof(sctp_sctphdr_t), count = 0;	\
 	offset < skb->len &&						\
-	(sch = skb_header_pointer(skb, offset, sizeof(_sch), &_sch));	\
-	offset += (htons(sch->length) + 3) & ~3, count++)
+	(sch = skb_header_pointer(skb, offset, sizeof(_sch), &_sch)) &&  \
+	sch->length; offset += (htons(sch->length) + 3) & ~3, count++)
 
 /* Some validity checks to make sure the chunks are fine */
 static int do_basic_checks(struct ip_conntrack *conntrack,
diff --git a/net/netfilter/nf_conntrack_proto_sctp.c b/net/netfilter/nf_conntrack_proto_sctp.c
index 9cccc32..2e34436 100644
--- a/net/netfilter/nf_conntrack_proto_sctp.c
+++ b/net/netfilter/nf_conntrack_proto_sctp.c
@@ -213,8 +213,8 @@ static int sctp_print_conntrack(struct s
 #define for_each_sctp_chunk(skb, sch, _sch, offset, dataoff, count)	\
 for (offset = dataoff + sizeof(sctp_sctphdr_t), count = 0;		\
 	offset < skb->len &&						\
-	(sch = skb_header_pointer(skb, offset, sizeof(_sch), &_sch));	\
-	offset += (htons(sch->length) + 3) & ~3, count++)
+	(sch = skb_header_pointer(skb, offset, sizeof(_sch), &_sch)) &&	\
+	sch->length; offset += (htons(sch->length) + 3) & ~3, count++)
 
 /* Some validity checks to make sure the chunks are fine */
 static int do_basic_checks(struct nf_conn *conntrack,