fib: fix load-balance and replicate dpos buckets overflow
load-balance and replicate dpos both store their number of buckets as
u16, which can overflow if too many paths are configured. For
load-balance it can happens quite quickly because of weights
normalization.
Type: fix
Change-Id: I0c78c39fc3d40626dfc58b49e7d99d71f9852b50
Signed-off-by: Benoît Ganne <bganne@cisco.com>
diff --git a/src/vnet/dpo/load_balance.c b/src/vnet/dpo/load_balance.c
index ff46d56..fae7c1d 100644
--- a/src/vnet/dpo/load_balance.c
+++ b/src/vnet/dpo/load_balance.c
@@ -244,6 +244,8 @@
{
load_balance_t *lb;
+ ASSERT (num_buckets <= LB_MAX_BUCKETS);
+
lb = load_balance_alloc_i();
lb->lb_hash_config = fhc;
lb->lb_n_buckets = num_buckets;
@@ -455,8 +457,9 @@
/* Try larger and larger power of 2 sized adjacency blocks until we
find one where traffic flows to within 1% of specified weights. */
- for (n_adj = max_pow2 (n_nhs); ; n_adj *= 2)
+ for (n_adj = clib_min(max_pow2 (n_nhs), LB_MAX_BUCKETS); ; n_adj *= 2)
{
+ ASSERT (n_adj <= LB_MAX_BUCKETS);
error = 0;
norm = n_adj / ((f64) sum_weight);
@@ -487,12 +490,22 @@
nhs[0].path_weight += n_adj_left;
- /* Less than 5% average error per adjacency with this size adjacency block? */
- if (error <= multipath_next_hop_error_tolerance*n_adj)
+ /* Less than 1% average error per adjacency with this size adjacency block,
+ * or did we reached the maximum number of buckets we support? */
+ if (error <= multipath_next_hop_error_tolerance*n_adj ||
+ n_adj >= LB_MAX_BUCKETS)
{
- /* Truncate any next hops with zero weight. */
- vec_set_len (nhs, i);
- break;
+ if (i < n_nhs)
+ {
+ /* Truncate any next hops in excess */
+ vlib_log_err(load_balance_logger,
+ "Too many paths for load-balance, truncating %d -> %d",
+ n_nhs, i);
+ for (int j = i; j < n_nhs; j++)
+ dpo_reset (&vec_elt(nhs, j).path_dpo);
+ }
+ vec_set_len (nhs, i);
+ break;
}
}
@@ -622,6 +635,7 @@
load_balance_set_n_buckets (load_balance_t *lb,
u32 n_buckets)
{
+ ASSERT (n_buckets <= LB_MAX_BUCKETS);
lb->lb_n_buckets = n_buckets;
lb->lb_n_buckets_minus_1 = n_buckets-1;
}
@@ -651,8 +665,6 @@
&sum_of_weights,
multipath_next_hop_error_tolerance);
- ASSERT (n_buckets >= vec_len (raw_nhs));
-
/*
* Save the old load-balance map used, and get a new one if required.
*/