sctp: fix association hangs due to off-by-one errors in sctp_tsnmap_grow()

In sctp_tsnmap_mark(), correct off-by-one error when calculating
size value for sctp_tsnmap_grow().

In sctp_tsnmap_grow(), correct off-by-one error when copying
and resizing the tsnmap.  If max_tsn_seen is in the LSB of the
word, this bit can be lost, causing the corresponding packet
to be transmitted again and to be entered as a duplicate into
the SCTP reassembly/ordering queues.  Change parameter name
from "gap" (zero-based index) to "size" (one-based) to enhance
code readability.

Signed-off-by: Lee A. Roberts <lee.roberts@hp.com>
Acked-by: Vlad Yasevich <vyasevich@gmail.com>
Acked-by: Neil Horman <nhorman@tuxdriver.com>

1 files changed, 7 insertions, 6 deletions

diff --git a/net/sctp/tsnmap.c b/net/sctp/tsnmap.c
index 5f25e0c92c31..396c45174e5b 100644
--- a/net/sctp/tsnmap.c
+++ b/net/sctp/tsnmap.c
@@ -51,7 +51,7 @@
 static void sctp_tsnmap_update(struct sctp_tsnmap *map);
 static void sctp_tsnmap_find_gap_ack(unsigned long *map, __u16 off,
                                      __u16 len, __u16 *start, __u16 *end);
-static int sctp_tsnmap_grow(struct sctp_tsnmap *map, u16 gap);
+static int sctp_tsnmap_grow(struct sctp_tsnmap *map, u16 size);
 
 /* Initialize a block of memory as a tsnmap.  */
 struct sctp_tsnmap *sctp_tsnmap_init(struct sctp_tsnmap *map, __u16 len,
@@ -124,7 +124,7 @@ int sctp_tsnmap_mark(struct sctp_tsnmap *map, __u32 tsn,
 
         gap = tsn - map->base_tsn;
 
-        if (gap >= map->len && !sctp_tsnmap_grow(map, gap))
+        if (gap >= map->len && !sctp_tsnmap_grow(map, gap + 1))
                 return -ENOMEM;
 
         if (!sctp_tsnmap_has_gap(map) && gap == 0) {
@@ -360,23 +360,24 @@ __u16 sctp_tsnmap_num_gabs(struct sctp_tsnmap *map,
         return ngaps;
 }
 
-static int sctp_tsnmap_grow(struct sctp_tsnmap *map, u16 gap)
+static int sctp_tsnmap_grow(struct sctp_tsnmap *map, u16 size)
 {
         unsigned long *new;
         unsigned long inc;
         u16  len;
 
-        if (gap >= SCTP_TSN_MAP_SIZE)
+        if (size > SCTP_TSN_MAP_SIZE)
                 return 0;
 
-        inc = ALIGN((gap - map->len),BITS_PER_LONG) + SCTP_TSN_MAP_INCREMENT;
+        inc = ALIGN((size - map->len), BITS_PER_LONG) + SCTP_TSN_MAP_INCREMENT;
         len = min_t(u16, map->len + inc, SCTP_TSN_MAP_SIZE);
 
         new = kzalloc(len>>3, GFP_ATOMIC);
         if (!new)
                 return 0;
 
-        bitmap_copy(new, map->tsn_map, map->max_tsn_seen - map->base_tsn);
+        bitmap_copy(new, map->tsn_map,
+                map->max_tsn_seen - map->cumulative_tsn_ack_point);
         kfree(map->tsn_map);
         map->tsn_map = new;
         map->len = len;