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>

diff --git a/net/sctp/tsnmap.c b/net/sctp/tsnmap.c
index 5f25e0c92c31e48460536cd2bb0fc29549172b93..396c45174e5b696d90c6940d7aa0ce511c70293c 100644 (file)
--- 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;