acl-plugin: tuplemerge: avoid batch-resize of the applied entries vector - VPP-1352

If the number of rules within a given partition exceeds the limit,
the split_partition() might get called, in which we calculate
the relaxed mask, create a new partition with that mask and
attempt to reallocate some entries from the overcrowded partition.

The non-TM code was pre-expanding the vector with rules by
the number of rules in the new ACL being applied - which
caused the split_partition() to iterate over the rules
filled with zeroes. Most of the time it is benign, but
if a newly created relaxed partition is such that these
entries can be "relocated", then the code attempts to
do so, which does not end well.

Change-Id: I2dbf3ccd29ff97277b21cdb11c4424ff0915c3b7
Signed-off-by: Andrew Yourtchenko <ayourtch@gmail.com>

1 files changed, 6 insertions, 2 deletions

diff --git a/src/plugins/acl/hash_lookup.c b/src/plugins/acl/hash_lookup.c
index f2913a933d0..c37aae44a98 100644
--- a/src/plugins/acl/hash_lookup.c
+++ b/src/plugins/acl/hash_lookup.c
@@ -734,12 +734,16 @@ hash_acl_apply(acl_main_t *am, u32 lc_index, int acl_index, u32 acl_position)
    * ACL, so the change adding this code also takes care of that.
    */
 
-  /* expand the applied aces vector by the necessary amount */
-  vec_resize((*applied_hash_aces), vec_len(ha->rules));
 
   vec_validate(am->hash_applied_mask_info_vec_by_lc_index, lc_index);
   /* add the rules from the ACL to the hash table for lookup and append to the vector*/
   for(i=0; i < vec_len(ha->rules); i++) {
+    /*
+     * Expand the applied aces vector to fit a new entry.
+     * One by one not to upset split_partition() if it is called.
+     */
+    vec_resize((*applied_hash_aces), 1);
+
     int is_ip6 = ha->rules[i].match.pkt.is_ip6;
     u32 new_index = base_offset + i;
     applied_hash_ace_entry_t *pae = vec_elt_at_index((*applied_hash_aces), new_index);