From ecc515d7238f2cffac839069d56dc271141defa0 Mon Sep 17 00:00:00 2001 From: Xin Long Date: Mon, 24 Oct 2016 01:01:09 +0800 Subject: [PATCH] sctp: fix the panic caused by route update 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 Acked-by: Neil Horman Signed-off-by: David S. Miller --- 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 2a5c1896d18f..6cb0df859195 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; } -- 2.20.1