[Ocfs2-devel] [PATCH v3] ocfs2: fix a panic problem caused by o2cb_ctl

[piaojun <piaojun@huawei.com>]

On 2019/1/28 10:01, Jia Guo wrote:
> In the process of creating a node, it will cause NULL pointer
> dereference in kernel if o2cb_ctl failed in the interval
> (mkdir, o2cb_set_node_attribute(node_num)] in function o2cb_add_node.
> 
> The node num is initialized to 0 in function o2nm_node_group_make_item,
> o2nm_node_group_drop_item will mistake the node number 0 for a
> valid node number when we delete the node before the node number is set
> correctly. If the local node number of the current host happens to be 0,
> cluster->cl_local_node will be set to O2NM_INVALID_NODE_NUM while
> o2hb_thread still running. The panic stack is generated as follows:
> 
> o2hb_thread
>     \-o2hb_do_disk_heartbeat
>         \-o2hb_check_own_slot
>             |-slot = &reg->hr_slots[o2nm_this_node()];
>             //o2nm_this_node() return O2NM_INVALID_NODE_NUM
> 
> We need to check whether the node number is set when we delete the node.
> 
> Signed-off-by: Jia Guo <guojia12@huawei.com>
> Reviewed-by: Joseph Qi <jiangqi903@gmail.com>
Acked-by: Jun Piao <piaojun@huawei.com>
> ---
>  fs/ocfs2/cluster/nodemanager.c | 14 ++++++++------
>  1 file changed, 8 insertions(+), 6 deletions(-)
> 
> diff --git a/fs/ocfs2/cluster/nodemanager.c b/fs/ocfs2/cluster/nodemanager.c
> index 0e4166c..4ac775e 100644
> --- a/fs/ocfs2/cluster/nodemanager.c
> +++ b/fs/ocfs2/cluster/nodemanager.c
> @@ -621,13 +621,15 @@ static void o2nm_node_group_drop_item(struct config_group *group,
>  	struct o2nm_node *node = to_o2nm_node(item);
>  	struct o2nm_cluster *cluster = to_o2nm_cluster(group->cg_item.ci_parent);
> 
> -	o2net_disconnect_node(node);
> +	if (cluster->cl_nodes[node->nd_num] == node) {
> +		o2net_disconnect_node(node);
> 
> -	if (cluster->cl_has_local &&
> -	    (cluster->cl_local_node == node->nd_num)) {
> -		cluster->cl_has_local = 0;
> -		cluster->cl_local_node = O2NM_INVALID_NODE_NUM;
> -		o2net_stop_listening(node);
> +		if (cluster->cl_has_local &&
> +		    (cluster->cl_local_node == node->nd_num)) {
> +			cluster->cl_has_local = 0;
> +			cluster->cl_local_node = O2NM_INVALID_NODE_NUM;
> +			o2net_stop_listening(node);
> +		}
>  	}
> 
>  	/* XXX call into net to stop this node from trading messages */
> 
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