On Mon, Oct 24, 2016 at 01:01:09AM +0800, Xin Long wrote:
> Commit 7303a1475008 ("sctp: identify chunks that need to be fragmented
> at IP level") made the chunk be fragmented at IP level in the next round
> if it's size exceed PMTU.
>
> But there still is another case, PMTU can be updated if transport's dst
> expires and transport's pmtu_pending is set in sctp_packet_transmit. If
> the new PMTU is less than the chunk, the same issue with that commit can
> be triggered.
>
> So we should drop this packet and let it retransmit in another round
> where it would be fragmented at IP level.
>
> This patch is to fix it by checking the chunk size after PMTU may be
> updated and dropping this packet if it's size exceed PMTU.
>
> Fixes: 90017accff61 ("sctp: Add GSO support")
> Signed-off-by: Xin Long <lucien.xin@xxxxxxxxx>
> ---
> net/sctp/output.c | 8 +++++++-
> 1 file changed, 7 insertions(+), 1 deletion(-)
>
> diff --git a/net/sctp/output.c b/net/sctp/output.c
> index 2a5c189..6cb0df8 100644
> --- a/net/sctp/output.c
> +++ b/net/sctp/output.c
> @@ -418,6 +418,7 @@ int sctp_packet_transmit(struct sctp_packet *packet, gfp_t gfp)
> __u8 has_data = 0;
> int gso = 0;
> int pktcount = 0;
> + int auth_len = 0;
> struct dst_entry *dst;
> unsigned char *auth = NULL; /* pointer to auth in skb data */
>
> @@ -510,7 +511,12 @@ int sctp_packet_transmit(struct sctp_packet *packet, gfp_t gfp)
> list_for_each_entry(chunk, &packet->chunk_list, list) {
> int padded = SCTP_PAD4(chunk->skb->len);
>
> - if (pkt_size + padded > tp->pathmtu)
> + if (chunk == packet->auth)
> + auth_len = padded;
> + else if (auth_len + padded + packet->overhead >
> + tp->pathmtu)
> + goto nomem;
> + else if (pkt_size + padded > tp->pathmtu)
> break;
> pkt_size += padded;
> }
> --
> 2.1.0
>
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>
Acked-by: Neil Horman <nhorman@xxxxxxxxxxxxx>
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