From a3007446e53af07c53bdb4cabad7b3ea60859da4 Mon Sep 17 00:00:00 2001 From: Marcelo Ricardo Leitner Date: Tue, 20 Sep 2016 18:19:13 -0300 Subject: [PATCH] sctp: fix the handling of SACK Gap Ack blocks sctp_acked() is using 32bit arithmetics on 16bits vars, via TSN_lte() macros, which is weird and confusing. Once the offset to ctsn is calculated, all wrapping is already handled and thus to verify the Gap Ack blocks we can just use pure less/big-or-equal than checks. Also, rename gap variable to tsn_offset, so it's more meaningful, as it doesn't point to any gap at all. Even so, I don't think this discrepancy resulted in any practical bug. This patch is a preparation for the next one, which will introduce typecheck() for TSN_lte() macros and would cause a compile error here. Suggested-by: David Laight Reported-by: David Laight Signed-off-by: Marcelo Ricardo Leitner Signed-off-by: David S. Miller --- net/sctp/outqueue.c | 11 ++++++----- 1 file changed, 6 insertions(+), 5 deletions(-) diff --git a/net/sctp/outqueue.c b/net/sctp/outqueue.c index 8c3f446d965c..3ec6da8bbb53 100644 --- a/net/sctp/outqueue.c +++ b/net/sctp/outqueue.c @@ -1719,7 +1719,7 @@ static int sctp_acked(struct sctp_sackhdr *sack, __u32 tsn) { int i; sctp_sack_variable_t *frags; - __u16 gap; + __u16 tsn_offset, blocks; __u32 ctsn = ntohl(sack->cum_tsn_ack); if (TSN_lte(tsn, ctsn)) @@ -1738,10 +1738,11 @@ static int sctp_acked(struct sctp_sackhdr *sack, __u32 tsn) */ frags = sack->variable; - gap = tsn - ctsn; - for (i = 0; i < ntohs(sack->num_gap_ack_blocks); ++i) { - if (TSN_lte(ntohs(frags[i].gab.start), gap) && - TSN_lte(gap, ntohs(frags[i].gab.end))) + blocks = ntohs(sack->num_gap_ack_blocks); + tsn_offset = tsn - ctsn; + for (i = 0; i < blocks; ++i) { + if (tsn_offset >= ntohs(frags[i].gab.start) && + tsn_offset <= ntohs(frags[i].gab.end)) goto pass; }