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Subject[PATCH 4.4 07/31] ocfs2: subsystem.su_mutex is required while accessing the item->ci_parent
Date
4.4-stable review patch.  If anyone has any objections, please let me know.

------------------

From: alex chen <alex.chen@huawei.com>

commit 853bc26a7ea39e354b9f8889ae7ad1492ffa28d2 upstream.

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.

[alex.chen@huawei.com: v2]
Link: http://lkml.kernel.org/r/59EEAA69.9080703@huawei.com
Link: http://lkml.kernel.org/r/59E9B36A.10700@huawei.com
Signed-off-by: Alex Chen <alex.chen@huawei.com>
Reviewed-by: Jun Piao <piaojun@huawei.com>
Reviewed-by: Joseph Qi <jiangqi903@gmail.com>
Cc: Mark Fasheh <mfasheh@versity.com>
Cc: Joel Becker <jlbec@evilplan.org>
Cc: Junxiao Bi <junxiao.bi@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Salvatore Bonaccorso <carnil@debian.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
fs/ocfs2/cluster/nodemanager.c | 63 +++++++++++++++++++++++++++++++++++------
1 file changed, 55 insertions(+), 8 deletions(-)

--- a/fs/ocfs2/cluster/nodemanager.c
+++ b/fs/ocfs2/cluster/nodemanager.c
@@ -40,6 +40,9 @@ char *o2nm_fence_method_desc[O2NM_FENCE_
"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_clus
{
/* 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(struc
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(struc
!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(struc
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_st
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_st
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_st
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(str
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(str
!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(str
cluster->cl_local_node = node->nd_num;
}

- return count;
+ ret = count;
+
+out:
+ o2nm_unlock_subsystem();
+ return ret;
}

CONFIGFS_ATTR(o2nm_node_, num);
@@ -750,6 +787,16 @@ static struct o2nm_cluster_group o2nm_cl
},
};

+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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