Arnaldo,
just a thought - I recall that there used to be a bug related to this,
which required to insert the following before sending an skb:
memset(&(IPCB(skb)->opt), 0, sizeof(IPCB(skb)->opt))
This was about 1+1/2 .. 2 years ago and lead to crashes when the memset
was removed. Maybe with this solution the memsets are then no longer
necessary? The reference is
* output.c:dccp_transmit_skb()
* ipv4.c:dccp_v4_send_response()
Gerrit
| commit eced67957ee99f7b5fafdc73a58bcd037a1789b2
| Author: Patrick McHardy <kaber@xxxxxxxxx>
| Date: Fri Apr 4 14:10:23 2008 +0200
|
| [DCCP]: Fix skb->cb conflicts with IP
|
| dev_queue_xmit() and the other IP output functions expect to get a skb
| with clear or properly initialized skb->cb. Unlike TCP and UDP, the
| dccp_skb_cb doesn't contain a struct inet_skb_parm at the beginning,
| so the DCCP-specific data is interpreted by the IP output functions.
| This can cause false negatives for the conditional POST_ROUTING hook
| invocation, making the packet bypass the hook.
|
| Add a inet_skb_parm/inet6_skb_parm union to the beginning of
| dccp_skb_cb to avoid clashes. Also add a BUILD_BUG_ON to make
| sure it fits in the cb.
|
| Signed-off-by: Patrick McHardy <kaber@xxxxxxxxx>
|
| diff --git a/net/dccp/dccp.h b/net/dccp/dccp.h
| index fe7726b..f44d492 100644
| --- a/net/dccp/dccp.h
| +++ b/net/dccp/dccp.h
| @@ -325,6 +325,12 @@ static inline int dccp_bad_service_code(const struct sock *sk,
| * This is used for transmission as well as for reception.
| */
| struct dccp_skb_cb {
| + union {
| + struct inet_skb_parm h4;
| +#if defined(CONFIG_IPV6) || defined (CONFIG_IPV6_MODULE)
| + struct inet6_skb_parm h6;
| +#endif
| + } header;
| __u8 dccpd_type:4;
| __u8 dccpd_ccval:4;
| __u8 dccpd_reset_code,
| diff --git a/net/dccp/proto.c b/net/dccp/proto.c
| index e3f5d37..c91d3c1 100644
| --- a/net/dccp/proto.c
| +++ b/net/dccp/proto.c
| @@ -1057,6 +1057,9 @@ static int __init dccp_init(void)
| int ehash_order, bhash_order, i;
| int rc = -ENOBUFS;
|
| + BUILD_BUG_ON(sizeof(struct dccp_skb_cb) >
| + FIELD_SIZEOF(struct sk_buff, cb));
| +
| dccp_hashinfo.bind_bucket_cachep =
| kmem_cache_create("dccp_bind_bucket",
| sizeof(struct inet_bind_bucket), 0,
--
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