Re: [PATCH] sctp: load transport header after sk_filter
From: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>
Date: 2016-07-18 11:59:10
On Sat, Jul 16, 2016 at 05:33:15PM -0400, Willem de Bruijn wrote:
From: Willem de Bruijn <willemb@google.com> Do not cache pointers into the skb linear segment across sk_filter. The function call can trigger pskb_expand_head. Signed-off-by: Willem de Bruijn <willemb@google.com>
Acked-by: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>
Just note that this change is included in 3acb50c18d8d ("sctp: delay
as much as possible skb_linearize") and accepting this one in net will
cause a conflict when merging them. Thanks
quoted hunk ↗ jump to hunk
--- No Fixes tag: existed at the start of git log. It is probably not necessary to store chunk->sctp_hdr at all, as chunk->skb exists. That is harder to verify, so not suitable for net. SCTP sk_filter trimming does not work as expected for most packets. sctp_inq_pop marks most truncated linear packets as discarded with pdiscard = 1. The following crude change would make trimming behave as expected on linear data chunks but is probably not safe as is. - if (unlikely(skb_is_nonlinear(chunk->skb))) { + if (1) { --- net/sctp/input.c | 5 +---- 1 file changed, 1 insertion(+), 4 deletions(-)diff --git a/net/sctp/input.c b/net/sctp/input.c index a701527..47cf460 100644 --- a/net/sctp/input.c +++ b/net/sctp/input.c@@ -112,7 +112,6 @@ int sctp_rcv(struct sk_buff *skb) struct sctp_ep_common *rcvr; struct sctp_transport *transport = NULL; struct sctp_chunk *chunk; - struct sctphdr *sh; union sctp_addr src; union sctp_addr dest; int family;@@ -127,8 +126,6 @@ int sctp_rcv(struct sk_buff *skb) if (skb_linearize(skb)) goto discard_it; - sh = sctp_hdr(skb); - /* Pull up the IP and SCTP headers. */ __skb_pull(skb, skb_transport_offset(skb)); if (skb->len < sizeof(struct sctphdr))@@ -230,7 +227,7 @@ int sctp_rcv(struct sk_buff *skb) chunk->rcvr = rcvr; /* Remember the SCTP header. */ - chunk->sctp_hdr = sh; + chunk->sctp_hdr = sctp_hdr(skb); /* Set the source and destination addresses of the incoming chunk. */ sctp_init_addrs(chunk, &src, &dest);-- 2.8.0.rc3.226.g39d4020