From 5c468674d17056148da06218d4da5d04baf22eac Mon Sep 17 00:00:00 2001 From: Xin Long Date: Mon, 18 Dec 2017 14:07:25 +0800 Subject: [PATCH] sctp: fix the issue that a __u16 variable may overflow in sctp_ulpq_renege Now when reneging events in sctp_ulpq_renege(), the variable freed could be increased by a __u16 value twice while freed is of __u16 type. It means freed may overflow at the second addition. This patch is to fix it by using __u32 type for 'freed', while at it, also to remove 'if (chunk)' check, as all renege commands are generated in sctp_eat_data and it can't be NULL. Reported-by: Marcelo Ricardo Leitner Signed-off-by: Xin Long Acked-by: Neil Horman Signed-off-by: David S. Miller --- net/sctp/ulpqueue.c | 24 ++++++++---------------- 1 file changed, 8 insertions(+), 16 deletions(-) diff --git a/net/sctp/ulpqueue.c b/net/sctp/ulpqueue.c index a71be33f3afe..e36ec5dd64c6 100644 --- a/net/sctp/ulpqueue.c +++ b/net/sctp/ulpqueue.c @@ -1084,29 +1084,21 @@ void sctp_ulpq_partial_delivery(struct sctp_ulpq *ulpq, void sctp_ulpq_renege(struct sctp_ulpq *ulpq, struct sctp_chunk *chunk, gfp_t gfp) { - struct sctp_association *asoc; - __u16 needed, freed; - - asoc = ulpq->asoc; + struct sctp_association *asoc = ulpq->asoc; + __u32 freed = 0; + __u16 needed; - if (chunk) { - needed = ntohs(chunk->chunk_hdr->length); - needed -= sizeof(struct sctp_data_chunk); - } else - needed = SCTP_DEFAULT_MAXWINDOW; - - freed = 0; + needed = ntohs(chunk->chunk_hdr->length) - + sizeof(struct sctp_data_chunk); if (skb_queue_empty(&asoc->base.sk->sk_receive_queue)) { freed = sctp_ulpq_renege_order(ulpq, needed); - if (freed < needed) { + if (freed < needed) freed += sctp_ulpq_renege_frags(ulpq, needed - freed); - } } /* If able to free enough room, accept this chunk. */ - if (chunk && (freed >= needed)) { - int retval; - retval = sctp_ulpq_tail_data(ulpq, chunk, gfp); + if (freed >= needed) { + int retval = sctp_ulpq_tail_data(ulpq, chunk, gfp); /* * Enter partial delivery if chunk has not been * delivered; otherwise, drain the reassembly queue. -- 2.30.2