4.15-stable review patch. If anyone has any objections, please let me know.
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From: Sowmini Varadhan sowmini.varadhan@oracle.com
commit f10b4cff98c6977668434fbf5dd58695eeca2897 upstream.
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 syzkaller@googlegroups.com Signed-off-by: Sowmini Varadhan sowmini.varadhan@oracle.com Acked-by: Santosh Shilimkar santosh.shilimkar@oracle.com Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- net/rds/tcp.c | 9 +++++++-- net/rds/tcp.h | 1 + 2 files changed, 8 insertions(+), 2 deletions(-)
--- a/net/rds/tcp.c +++ b/net/rds/tcp.c @@ -307,7 +307,8 @@ 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); @@ -532,8 +533,12 @@ static void rds_tcp_kill_sock(struct 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) { --- a/net/rds/tcp.h +++ b/net/rds/tcp.h @@ -12,6 +12,7 @@ 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