[ovs-dev] [PATCH v3 1/8] conntrack: Init hash basis first at creation

Gaetan Rivet grive at u256.net
Tue Jun 15 23:22:46 UTC 2021


The 'hash_basis' field is used sometimes during sub-systems init
routine. It will be 0 by default before randomization. Sub-systems would
then init some nodes with incorrect hash values.

The timeout policies module is affected, making the default policy being
referenced using an incorrect hash value.

Fixes: 2078901a4c14 ("userspace: Add conntrack timeout policy support.")
Signed-off-by: Gaetan Rivet <grive at u256.net>
Reviewed-by: Eli Britstein <elibr at nvidia.com>
Acked-by: William Tu <u9012063 at gmail.com>
---
 lib/conntrack.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/lib/conntrack.c b/lib/conntrack.c
index 99198a601..a5efb37aa 100644
--- a/lib/conntrack.c
+++ b/lib/conntrack.c
@@ -291,6 +291,11 @@ conntrack_init(void)
     static struct ovsthread_once setup_l4_once = OVSTHREAD_ONCE_INITIALIZER;
     struct conntrack *ct = xzalloc(sizeof *ct);
 
+    /* This value can be used during init (e.g. timeout_policy_init()),
+     * set it first to ensure it is available.
+     */
+    ct->hash_basis = random_uint32();
+
     ovs_rwlock_init(&ct->resources_lock);
     ovs_rwlock_wrlock(&ct->resources_lock);
     hmap_init(&ct->alg_expectations);
@@ -308,7 +313,6 @@ conntrack_init(void)
     timeout_policy_init(ct);
     ovs_mutex_unlock(&ct->ct_lock);
 
-    ct->hash_basis = random_uint32();
     atomic_count_init(&ct->n_conn, 0);
     atomic_init(&ct->n_conn_limit, DEFAULT_N_CONN_LIMIT);
     atomic_init(&ct->tcp_seq_chk, true);
-- 
2.31.1



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