The rds_tcp_kill_sock() function parses the rds_tcp_conn_list
to find the rds_connection entries marked for deletion as part
of the netns deletion under the protection of the rds_tcp_conn_lock.
Since the rds_tcp_conn_list tracks rds_tcp_connections (which
have a 1:1 mapping with rds_conn_path), multiple tc entries in
the rds_tcp_conn_list will map to a single rds_connection, and will
be deleted as part of the rds_conn_destroy() operation that is
done outside the rds_tcp_conn_lock.
The rds_tcp_conn_list traversal done under the protection of
rds_tcp_conn_lock should not leave any doomed tc entries in
the list after the rds_tcp_conn_lock is released, else another
concurrently executiong netns delete (for a differnt netns) thread
may trip on these entries.
Reported-by: syzbot <syzkal...@googlegroups.com>
Signed-off-by: Sowmini Varadhan <sowmini.varad...@oracle.com>
---
net/rds/tcp.c | 9 +++++++--
net/rds/tcp.h | 1 +
2 files changed, 8 insertions(+), 2 deletions(-)
diff --git a/net/rds/tcp.c b/net/rds/tcp.c
index f580f72..39f502d 100644
--- a/net/rds/tcp.c
+++ b/net/rds/tcp.c
@@ -306,7 +306,8 @@ static void rds_tcp_conn_free(void *arg)
rdsdebug("freeing tc %p\n", tc);
spin_lock_irqsave(&rds_tcp_conn_lock, flags);
- list_del(&tc->t_tcp_node);
+ if (!tc->t_tcp_node_detached)
+ list_del(&tc->t_tcp_node);
spin_unlock_irqrestore(&rds_tcp_conn_lock, flags);
kmem_cache_free(rds_tcp_conn_slab, tc);
@@ -510,8 +511,12 @@ static void rds_tcp_kill_sock(struct net *net)
if (net != c_net || !tc->t_sock)
continue;
- if (!list_has_conn(&tmp_list, tc->t_cpath->cp_conn))
+ if (!list_has_conn(&tmp_list, tc->t_cpath->cp_conn)) {
list_move_tail(&tc->t_tcp_node, &tmp_list);
+ } else {
+ list_del(&tc->t_tcp_node);
+ tc->t_tcp_node_detached = true;
+ }
}
spin_unlock_irq(&rds_tcp_conn_lock);
list_for_each_entry_safe(tc, _tc, &tmp_list, t_tcp_node)
diff --git a/net/rds/tcp.h b/net/rds/tcp.h
index f8800b7..8775349 100644
--- a/net/rds/tcp.h
+++ b/net/rds/tcp.h
@@ -11,6 +11,7 @@ struct rds_tcp_incoming {
struct rds_tcp_connection {
struct list_head t_tcp_node;
+ bool t_tcp_node_detached;
struct rds_conn_path *t_cpath;
/* t_conn_path_lock synchronizes the connection establishment between
* rds_tcp_accept_one and rds_tcp_conn_path_connect
--
1.7.1
