[Ocfs2-devel] [PATCH v2] ocfs2: subsystem.su_mutex is required while accessing the item->ci_parent
Joseph Qi
jiangqi903 at gmail.com
Mon Oct 23 20:45:04 PDT 2017
On 17/10/24 10:50, alex chen wrote:
> The subsystem.su_mutex is required while accessing the item->ci_parent,
> otherwise, NULL pointer dereference to the item->ci_parent will be
> triggered in the following situation:
> add node delete node
> sys_write
> vfs_write
> configfs_write_file
> o2nm_node_store
> o2nm_node_local_write
> do_rmdir
> vfs_rmdir
> configfs_rmdir
> mutex_lock(&subsys->su_mutex);
> unlink_obj
> item->ci_group = NULL;
> item->ci_parent = NULL;
> to_o2nm_cluster_from_node
> node->nd_item.ci_parent->ci_parent
> BUG since of NULL pointer dereference to nd_item.ci_parent
>
> Moreover, the o2nm_cluster also should be protected by the subsystem.su_mutex.
>
> Signed-off-by: Alex Chen <alex.chen at huawei.com>
> Reviewed-by: Jun Piao <piaojun at huawei.com>
Reviewed-by: Joseph Qi <jiangqi903 at gmail.com>
>
> ---
> fs/ocfs2/cluster/nodemanager.c | 63 ++++++++++++++++++++++++++++++++++++------
> 1 file changed, 55 insertions(+), 8 deletions(-)
>
> diff --git a/fs/ocfs2/cluster/nodemanager.c b/fs/ocfs2/cluster/nodemanager.c
> index b17d180..c204ac9b 100644
> --- a/fs/ocfs2/cluster/nodemanager.c
> +++ b/fs/ocfs2/cluster/nodemanager.c
> @@ -40,6 +40,9 @@
> "panic", /* O2NM_FENCE_PANIC */
> };
>
> +static inline void o2nm_lock_subsystem(void);
> +static inline void o2nm_unlock_subsystem(void);
> +
> struct o2nm_node *o2nm_get_node_by_num(u8 node_num)
> {
> struct o2nm_node *node = NULL;
> @@ -181,7 +184,10 @@ static struct o2nm_cluster *to_o2nm_cluster_from_node(struct o2nm_node *node)
> {
> /* through the first node_set .parent
> * mycluster/nodes/mynode == o2nm_cluster->o2nm_node_group->o2nm_node */
> - return to_o2nm_cluster(node->nd_item.ci_parent->ci_parent);
> + if (node->nd_item.ci_parent)
> + return to_o2nm_cluster(node->nd_item.ci_parent->ci_parent);
> + else
> + return NULL;
> }
>
> enum {
> @@ -194,7 +200,7 @@ static ssize_t o2nm_node_num_store(struct config_item *item, const char *page,
> size_t count)
> {
> struct o2nm_node *node = to_o2nm_node(item);
> - struct o2nm_cluster *cluster = to_o2nm_cluster_from_node(node);
> + struct o2nm_cluster *cluster;
> unsigned long tmp;
> char *p = (char *)page;
> int ret = 0;
> @@ -214,6 +220,13 @@ static ssize_t o2nm_node_num_store(struct config_item *item, const char *page,
> !test_bit(O2NM_NODE_ATTR_PORT, &node->nd_set_attributes))
> return -EINVAL; /* XXX */
>
> + o2nm_lock_subsystem();
> + cluster = to_o2nm_cluster_from_node(node);
> + if (!cluster) {
> + o2nm_unlock_subsystem();
> + return -EINVAL;
> + }
> +
> write_lock(&cluster->cl_nodes_lock);
> if (cluster->cl_nodes[tmp])
> ret = -EEXIST;
> @@ -226,6 +239,8 @@ static ssize_t o2nm_node_num_store(struct config_item *item, const char *page,
> set_bit(tmp, cluster->cl_nodes_bitmap);
> }
> write_unlock(&cluster->cl_nodes_lock);
> + o2nm_unlock_subsystem();
> +
> if (ret)
> return ret;
>
> @@ -269,7 +284,7 @@ static ssize_t o2nm_node_ipv4_address_store(struct config_item *item,
> size_t count)
> {
> struct o2nm_node *node = to_o2nm_node(item);
> - struct o2nm_cluster *cluster = to_o2nm_cluster_from_node(node);
> + struct o2nm_cluster *cluster;
> int ret, i;
> struct rb_node **p, *parent;
> unsigned int octets[4];
> @@ -286,6 +301,13 @@ static ssize_t o2nm_node_ipv4_address_store(struct config_item *item,
> be32_add_cpu(&ipv4_addr, octets[i] << (i * 8));
> }
>
> + o2nm_lock_subsystem();
> + cluster = to_o2nm_cluster_from_node(node);
> + if (!cluster) {
> + o2nm_unlock_subsystem();
> + return -EINVAL;
> + }
> +
> ret = 0;
> write_lock(&cluster->cl_nodes_lock);
> if (o2nm_node_ip_tree_lookup(cluster, ipv4_addr, &p, &parent))
> @@ -298,6 +320,8 @@ static ssize_t o2nm_node_ipv4_address_store(struct config_item *item,
> rb_insert_color(&node->nd_ip_node, &cluster->cl_node_ip_tree);
> }
> write_unlock(&cluster->cl_nodes_lock);
> + o2nm_unlock_subsystem();
> +
> if (ret)
> return ret;
>
> @@ -315,7 +339,7 @@ static ssize_t o2nm_node_local_store(struct config_item *item, const char *page,
> size_t count)
> {
> struct o2nm_node *node = to_o2nm_node(item);
> - struct o2nm_cluster *cluster = to_o2nm_cluster_from_node(node);
> + struct o2nm_cluster *cluster;
> unsigned long tmp;
> char *p = (char *)page;
> ssize_t ret;
> @@ -333,17 +357,26 @@ static ssize_t o2nm_node_local_store(struct config_item *item, const char *page,
> !test_bit(O2NM_NODE_ATTR_PORT, &node->nd_set_attributes))
> return -EINVAL; /* XXX */
>
> + o2nm_lock_subsystem();
> + cluster = to_o2nm_cluster_from_node(node);
> + if (!cluster) {
> + ret = -EINVAL;
> + goto out;
> + }
> +
> /* the only failure case is trying to set a new local node
> * when a different one is already set */
> if (tmp && tmp == cluster->cl_has_local &&
> - cluster->cl_local_node != node->nd_num)
> - return -EBUSY;
> + cluster->cl_local_node != node->nd_num) {
> + ret = -EBUSY;
> + goto out;
> + }
>
> /* bring up the rx thread if we're setting the new local node. */
> if (tmp && !cluster->cl_has_local) {
> ret = o2net_start_listening(node);
> if (ret)
> - return ret;
> + goto out;
> }
>
> if (!tmp && cluster->cl_has_local &&
> @@ -358,7 +391,11 @@ static ssize_t o2nm_node_local_store(struct config_item *item, const char *page,
> cluster->cl_local_node = node->nd_num;
> }
>
> - return count;
> + ret = count;
> +
> +out:
> + o2nm_unlock_subsystem();
> + return ret;
> }
>
> CONFIGFS_ATTR(o2nm_node_, num);
> @@ -738,6 +775,16 @@ static void o2nm_cluster_group_drop_item(struct config_group *group, struct conf
> },
> };
>
> +static inline void o2nm_lock_subsystem(void)
> +{
> + mutex_lock(&o2nm_cluster_group.cs_subsys.su_mutex);
> +}
> +
> +static inline void o2nm_unlock_subsystem(void)
> +{
> + mutex_unlock(&o2nm_cluster_group.cs_subsys.su_mutex);
> +}
> +
> int o2nm_depend_item(struct config_item *item)
> {
> return configfs_depend_item(&o2nm_cluster_group.cs_subsys, item);
>
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