We found a NULL pointer dereference in iscsi_sw_tcp_conn_get_param(),
the root reason is we did sysfs addition wrong.
iscsi_create_conn() expose iscsi_cls_conn to sysfs while the related
resources are not initialized. So we should delay the calling of
device_add() until these resources has been initialized.
This patchset solve this issue by correct the add and teardown flow
of iscsi_cls_conn.
-----------
V2:
add two more iscsi_free_conn() and iscsi_remove_conn() than V1
change the teardown flow of iscsi_cls_conn
Wenchao Hao (3):
scsi: iscsi: Add helper functions to manage iscsi_cls_conn
scsi:libiscsi: Add iscsi_cls_conn to sysfs after been initialized
scsi:libiscsi: teardown iscsi_cls_conn gracefully
drivers/scsi/libiscsi.c | 21 ++++++---
drivers/scsi/scsi_transport_iscsi.c | 72 +++++++++++++++++++++--------
include/scsi/scsi_transport_iscsi.h | 5 +-
3 files changed, 71 insertions(+), 27 deletions(-)
--
2.32.0
iscsi_create_conn() would expose iscsi_cls_conn to sysfs, while the
initialization of iscsi_conn's dd_data is not ready now. When userspace
try to access an attribute such as connect's address, it might cause
a NULL pointer dereference.
So we should add iscsi_cls_conn to sysfs until it has been initialized.
Remove iscsi_create_conn() by hand since it is not used now.
Signed-off-by: Wenchao Hao <[email protected]>
Signed-off-by: Wu Bo <[email protected]>
---
drivers/scsi/libiscsi.c | 13 ++++-
drivers/scsi/scsi_transport_iscsi.c | 76 -----------------------------
include/scsi/scsi_transport_iscsi.h | 2 -
3 files changed, 11 insertions(+), 80 deletions(-)
diff --git a/drivers/scsi/libiscsi.c b/drivers/scsi/libiscsi.c
index 059dae8909ee..43f903bce0b8 100644
--- a/drivers/scsi/libiscsi.c
+++ b/drivers/scsi/libiscsi.c
@@ -3040,8 +3040,9 @@ iscsi_conn_setup(struct iscsi_cls_session *cls_session, int dd_size,
struct iscsi_conn *conn;
struct iscsi_cls_conn *cls_conn;
char *data;
+ int err;
- cls_conn = iscsi_create_conn(cls_session, sizeof(*conn) + dd_size,
+ cls_conn = iscsi_alloc_conn(cls_session, sizeof(*conn) + dd_size,
conn_idx);
if (!cls_conn)
return NULL;
@@ -3078,13 +3079,21 @@ iscsi_conn_setup(struct iscsi_cls_session *cls_session, int dd_size,
goto login_task_data_alloc_fail;
conn->login_task->data = conn->data = data;
+ err = iscsi_add_conn(cls_conn);
+ if (err)
+ goto login_task_add_dev_fail;
+
return cls_conn;
+login_task_add_dev_fail:
+ free_pages((unsigned long) conn->data,
+ get_order(ISCSI_DEF_MAX_RECV_SEG_LEN));
+
login_task_data_alloc_fail:
kfifo_in(&session->cmdpool.queue, (void*)&conn->login_task,
sizeof(void*));
login_task_alloc_fail:
- iscsi_destroy_conn(cls_conn);
+ iscsi_free_conn(cls_conn);
return NULL;
}
EXPORT_SYMBOL_GPL(iscsi_conn_setup);
diff --git a/drivers/scsi/scsi_transport_iscsi.c b/drivers/scsi/scsi_transport_iscsi.c
index 8e97c6f88359..ca724eed4f4d 100644
--- a/drivers/scsi/scsi_transport_iscsi.c
+++ b/drivers/scsi/scsi_transport_iscsi.c
@@ -2447,82 +2447,6 @@ void iscsi_free_conn(struct iscsi_cls_conn *conn)
}
EXPORT_SYMBOL_GPL(iscsi_free_conn);
-/**
- * iscsi_create_conn - create iscsi class connection
- * @session: iscsi cls session
- * @dd_size: private driver data size
- * @cid: connection id
- *
- * This can be called from a LLD or iscsi_transport. The connection
- * is child of the session so cid must be unique for all connections
- * on the session.
- *
- * Since we do not support MCS, cid will normally be zero. In some cases
- * for software iscsi we could be trying to preallocate a connection struct
- * in which case there could be two connection structs and cid would be
- * non-zero.
- */
-struct iscsi_cls_conn *
-iscsi_create_conn(struct iscsi_cls_session *session, int dd_size, uint32_t cid)
-{
- struct iscsi_transport *transport = session->transport;
- struct iscsi_cls_conn *conn;
- unsigned long flags;
- int err;
-
- conn = kzalloc(sizeof(*conn) + dd_size, GFP_KERNEL);
- if (!conn)
- return NULL;
- if (dd_size)
- conn->dd_data = &conn[1];
-
- mutex_init(&conn->ep_mutex);
- INIT_LIST_HEAD(&conn->conn_list);
- INIT_WORK(&conn->cleanup_work, iscsi_cleanup_conn_work_fn);
- conn->transport = transport;
- conn->cid = cid;
- conn->state = ISCSI_CONN_DOWN;
-
- /* this is released in the dev's release function */
- if (!get_device(&session->dev))
- goto free_conn;
-
- dev_set_name(&conn->dev, "connection%d:%u", session->sid, cid);
- conn->dev.parent = &session->dev;
- conn->dev.release = iscsi_conn_release;
- err = device_register(&conn->dev);
- if (err) {
- iscsi_cls_session_printk(KERN_ERR, session, "could not "
- "register connection's dev\n");
- goto release_parent_ref;
- }
- err = transport_register_device(&conn->dev);
- if (err) {
- iscsi_cls_session_printk(KERN_ERR, session, "could not "
- "register transport's dev\n");
- goto release_conn_ref;
- }
-
- spin_lock_irqsave(&connlock, flags);
- list_add(&conn->conn_list, &connlist);
- spin_unlock_irqrestore(&connlock, flags);
-
- ISCSI_DBG_TRANS_CONN(conn, "Completed conn creation\n");
- return conn;
-
-release_conn_ref:
- device_unregister(&conn->dev);
- put_device(&session->dev);
- return NULL;
-release_parent_ref:
- put_device(&session->dev);
-free_conn:
- kfree(conn);
- return NULL;
-}
-
-EXPORT_SYMBOL_GPL(iscsi_create_conn);
-
/**
* iscsi_destroy_conn - destroy iscsi class connection
* @conn: iscsi cls session
diff --git a/include/scsi/scsi_transport_iscsi.h b/include/scsi/scsi_transport_iscsi.h
index 346f65bc3861..505764942f5e 100644
--- a/include/scsi/scsi_transport_iscsi.h
+++ b/include/scsi/scsi_transport_iscsi.h
@@ -446,8 +446,6 @@ extern struct iscsi_cls_conn *iscsi_alloc_conn(struct iscsi_cls_session *sess,
extern int iscsi_add_conn(struct iscsi_cls_conn *conn);
extern void iscsi_remove_conn(struct iscsi_cls_conn *conn);
extern void iscsi_free_conn(struct iscsi_cls_conn *conn);
-extern struct iscsi_cls_conn *iscsi_create_conn(struct iscsi_cls_session *sess,
- int dd_size, uint32_t cid);
extern void iscsi_put_conn(struct iscsi_cls_conn *conn);
extern void iscsi_get_conn(struct iscsi_cls_conn *conn);
extern int iscsi_destroy_conn(struct iscsi_cls_conn *conn);
--
2.32.0
commit 1b8d0300a3e9 ("scsi: libiscsi: Fix UAF in
iscsi_conn_get_param()/iscsi_conn_teardown()") fixed an UAF in
iscsi_conn_get_param() and introduced 2 tmp_xxx varibles, the
implement looks ugly.
We can fix this UAF with the help of device_del() gracefully.
Call iscsi_remove_conn() at the beginning of iscsi_conn_teardown would
make userspace unable to see iscsi_cls_conn any more, then we can free
memory safely.
Signed-off-by: Wenchao Hao <[email protected]>
Signed-off-by: Wu Bo <[email protected]>
---
drivers/scsi/libiscsi.c | 8 ++++----
drivers/scsi/scsi_transport_iscsi.c | 3 ++-
2 files changed, 6 insertions(+), 5 deletions(-)
diff --git a/drivers/scsi/libiscsi.c b/drivers/scsi/libiscsi.c
index 43f903bce0b8..0d57521751dd 100644
--- a/drivers/scsi/libiscsi.c
+++ b/drivers/scsi/libiscsi.c
@@ -3109,8 +3109,8 @@ void iscsi_conn_teardown(struct iscsi_cls_conn *cls_conn)
{
struct iscsi_conn *conn = cls_conn->dd_data;
struct iscsi_session *session = conn->session;
- char *tmp_persistent_address = conn->persistent_address;
- char *tmp_local_ipaddr = conn->local_ipaddr;
+
+ iscsi_remove_conn(cls_conn);
del_timer_sync(&conn->transport_timer);
@@ -3132,6 +3132,8 @@ void iscsi_conn_teardown(struct iscsi_cls_conn *cls_conn)
spin_lock_bh(&session->frwd_lock);
free_pages((unsigned long) conn->data,
get_order(ISCSI_DEF_MAX_RECV_SEG_LEN));
+ kfree(conn->persistent_address);
+ kfree(conn->local_ipaddr);
/* regular RX path uses back_lock */
spin_lock_bh(&session->back_lock);
kfifo_in(&session->cmdpool.queue, (void*)&conn->login_task,
@@ -3143,8 +3145,6 @@ void iscsi_conn_teardown(struct iscsi_cls_conn *cls_conn)
mutex_unlock(&session->eh_mutex);
iscsi_destroy_conn(cls_conn);
- kfree(tmp_persistent_address);
- kfree(tmp_local_ipaddr);
}
EXPORT_SYMBOL_GPL(iscsi_conn_teardown);
diff --git a/drivers/scsi/scsi_transport_iscsi.c b/drivers/scsi/scsi_transport_iscsi.c
index ca724eed4f4d..7b4d998708e7 100644
--- a/drivers/scsi/scsi_transport_iscsi.c
+++ b/drivers/scsi/scsi_transport_iscsi.c
@@ -2165,6 +2165,7 @@ static int iscsi_iter_destroy_conn_fn(struct device *dev, void *data)
{
if (!iscsi_is_conn_dev(dev))
return 0;
+ iscsi_remove_conn(iscsi_dev_to_conn(dev));
return iscsi_destroy_conn(iscsi_dev_to_conn(dev));
}
@@ -2463,7 +2464,7 @@ int iscsi_destroy_conn(struct iscsi_cls_conn *conn)
transport_unregister_device(&conn->dev);
ISCSI_DBG_TRANS_CONN(conn, "Completing conn destruction\n");
- device_unregister(&conn->dev);
+ iscsi_free_conn(conn);
return 0;
}
EXPORT_SYMBOL_GPL(iscsi_destroy_conn);
--
2.32.0
On 3/8/22 9:09 PM, Wenchao Hao wrote:
> @@ -3143,8 +3145,6 @@ void iscsi_conn_teardown(struct iscsi_cls_conn *cls_conn)
> mutex_unlock(&session->eh_mutex);
>
> iscsi_destroy_conn(cls_conn);
This should then be a iscsi_put_conn.
So basically it balances out.
iscsi_alloc_conn requires iscsi_put_conn. The put releases what is
done in the alloc. The put on the parent is done in the release though.
iscsi_add_conn requires iscsi_remove_conn. The remove undoes what
was done in the add
We don't want a iscsi_destroy_conn which does a iscsi_free_conn
because it makes it confusing.
iscsi_alloc_conn(): alloc and initialize iscsi_cls_conn
iscsi_add_conn(): expose iscsi_cls_conn to userspace's via sysfs.
iscsi_remove_conn(): remove iscsi_cls_conn from sysfs
iscsi_free_conn(): free iscsi_cls_conn
Signed-off-by: Wenchao Hao <[email protected]>
Signed-off-by: Wu Bo <[email protected]>
---
drivers/scsi/scsi_transport_iscsi.c | 107 ++++++++++++++++++++++++++++
include/scsi/scsi_transport_iscsi.h | 5 ++
2 files changed, 112 insertions(+)
diff --git a/drivers/scsi/scsi_transport_iscsi.c b/drivers/scsi/scsi_transport_iscsi.c
index 554b6f784223..8e97c6f88359 100644
--- a/drivers/scsi/scsi_transport_iscsi.c
+++ b/drivers/scsi/scsi_transport_iscsi.c
@@ -2340,6 +2340,113 @@ void iscsi_free_session(struct iscsi_cls_session *session)
}
EXPORT_SYMBOL_GPL(iscsi_free_session);
+/**
+ * iscsi_alloc_conn - alloc iscsi class connection
+ * @session: iscsi cls session
+ * @dd_size: private driver data size
+ * @cid: connection id
+ *
+ * This can be called from a LLD or iscsi_transport. The connection
+ * is child of the session so cid must be unique for all connections
+ * on the session.
+ *
+ * Since we do not support MCS, cid will normally be zero. In some cases
+ * for software iscsi we could be trying to preallocate a connection struct
+ * in which case there could be two connection structs and cid would be
+ * non-zero.
+ */
+struct iscsi_cls_conn *
+iscsi_alloc_conn(struct iscsi_cls_session *session, int dd_size, uint32_t cid)
+{
+ struct iscsi_transport *transport = session->transport;
+ struct iscsi_cls_conn *conn;
+
+ conn = kzalloc(sizeof(*conn) + dd_size, GFP_KERNEL);
+ if (!conn)
+ return NULL;
+ if (dd_size)
+ conn->dd_data = &conn[1];
+
+ mutex_init(&conn->ep_mutex);
+ INIT_LIST_HEAD(&conn->conn_list);
+ INIT_WORK(&conn->cleanup_work, iscsi_cleanup_conn_work_fn);
+ conn->transport = transport;
+ conn->cid = cid;
+ conn->state = ISCSI_CONN_DOWN;
+
+ /* this is released in the dev's release function */
+ if (!get_device(&session->dev))
+ goto free_conn;
+
+ dev_set_name(&conn->dev, "connection%d:%u", session->sid, cid);
+ device_initialize(&conn->dev);
+ conn->dev.parent = &session->dev;
+ conn->dev.release = iscsi_conn_release;
+
+ return conn;
+
+free_conn:
+ kfree(conn);
+ return NULL;
+}
+EXPORT_SYMBOL_GPL(iscsi_alloc_conn);
+
+/**
+ * iscsi_add_conn - add iscsi class connection
+ * @conn: iscsi cls connection
+ *
+ * this would expose iscsi_cls_conn to sysfs, so make sure the related
+ * resources when access sysfs attributes are initialized before calling this.
+ */
+int iscsi_add_conn(struct iscsi_cls_conn *conn)
+{
+ int err;
+ unsigned long flags;
+ struct iscsi_cls_session *session = iscsi_dev_to_session(conn->dev.parent);
+
+ err = device_add(&conn->dev);
+ if (err) {
+ iscsi_cls_session_printk(KERN_ERR, session,
+ "could not register connection's dev\n");
+ put_device(&session->dev);
+ return err;
+ }
+ err = transport_register_device(&conn->dev);
+ if (err) {
+ iscsi_cls_session_printk(KERN_ERR, session,
+ "could not register transport's dev\n");
+ device_del(&conn->dev);
+ put_device(&session->dev);
+ return err;
+ }
+
+ spin_lock_irqsave(&connlock, flags);
+ list_add(&conn->conn_list, &connlist);
+ spin_unlock_irqrestore(&connlock, flags);
+
+ return 0;
+}
+EXPORT_SYMBOL_GPL(iscsi_add_conn);
+
+/**
+ * iscsi_remove_conn - remove iscsi class connection from sysfs
+ * @conn: iscsi cls connection
+ *
+ * this would remove iscsi_cls_conn from sysfs, and wait for previous
+ * read/write of iscsi_cls_conn's attributes in sysfs finishing
+ */
+void iscsi_remove_conn(struct iscsi_cls_conn *conn)
+{
+ device_del(&conn->dev);
+}
+EXPORT_SYMBOL_GPL(iscsi_remove_conn);
+
+void iscsi_free_conn(struct iscsi_cls_conn *conn)
+{
+ put_device(&conn->dev);
+}
+EXPORT_SYMBOL_GPL(iscsi_free_conn);
+
/**
* iscsi_create_conn - create iscsi class connection
* @session: iscsi cls session
diff --git a/include/scsi/scsi_transport_iscsi.h b/include/scsi/scsi_transport_iscsi.h
index c5d7810fd792..346f65bc3861 100644
--- a/include/scsi/scsi_transport_iscsi.h
+++ b/include/scsi/scsi_transport_iscsi.h
@@ -441,6 +441,11 @@ extern struct iscsi_cls_session *iscsi_create_session(struct Scsi_Host *shost,
unsigned int target_id);
extern void iscsi_remove_session(struct iscsi_cls_session *session);
extern void iscsi_free_session(struct iscsi_cls_session *session);
+extern struct iscsi_cls_conn *iscsi_alloc_conn(struct iscsi_cls_session *sess,
+ int dd_size, uint32_t cid);
+extern int iscsi_add_conn(struct iscsi_cls_conn *conn);
+extern void iscsi_remove_conn(struct iscsi_cls_conn *conn);
+extern void iscsi_free_conn(struct iscsi_cls_conn *conn);
extern struct iscsi_cls_conn *iscsi_create_conn(struct iscsi_cls_session *sess,
int dd_size, uint32_t cid);
extern void iscsi_put_conn(struct iscsi_cls_conn *conn);
--
2.32.0
On 3/8/22 9:09 PM, Wenchao Hao wrote:
> iscsi_alloc_conn(): alloc and initialize iscsi_cls_conn
> iscsi_add_conn(): expose iscsi_cls_conn to userspace's via sysfs.
> iscsi_remove_conn(): remove iscsi_cls_conn from sysfs
> iscsi_free_conn(): free iscsi_cls_conn
>
> Signed-off-by: Wenchao Hao <[email protected]>
> Signed-off-by: Wu Bo <[email protected]>
> ---
> drivers/scsi/scsi_transport_iscsi.c | 107 ++++++++++++++++++++++++++++
> include/scsi/scsi_transport_iscsi.h | 5 ++
> 2 files changed, 112 insertions(+)
>
> diff --git a/drivers/scsi/scsi_transport_iscsi.c b/drivers/scsi/scsi_transport_iscsi.c
> index 554b6f784223..8e97c6f88359 100644
> --- a/drivers/scsi/scsi_transport_iscsi.c
> +++ b/drivers/scsi/scsi_transport_iscsi.c
> @@ -2340,6 +2340,113 @@ void iscsi_free_session(struct iscsi_cls_session *session)
> }
> EXPORT_SYMBOL_GPL(iscsi_free_session);
>
> +/**
> + * iscsi_alloc_conn - alloc iscsi class connection
> + * @session: iscsi cls session
> + * @dd_size: private driver data size
> + * @cid: connection id
> + *
> + * This can be called from a LLD or iscsi_transport. The connection
> + * is child of the session so cid must be unique for all connections
> + * on the session.
> + *
> + * Since we do not support MCS, cid will normally be zero. In some cases
> + * for software iscsi we could be trying to preallocate a connection struct
> + * in which case there could be two connection structs and cid would be
> + * non-zero.
Is that with the upstream iscsi tools or your version? I don't think the comment
is needed or is needed somewhere else.
If this happens then they will have the same sysfs/device name so when we do the
device_add it will spit an error about duplicate names.
> + */
> +struct iscsi_cls_conn *
> +iscsi_alloc_conn(struct iscsi_cls_session *session, int dd_size, uint32_t cid)
> +{
> + struct iscsi_transport *transport = session->transport;
> + struct iscsi_cls_conn *conn;
> +
> + conn = kzalloc(sizeof(*conn) + dd_size, GFP_KERNEL);
> + if (!conn)
> + return NULL;
> + if (dd_size)
> + conn->dd_data = &conn[1];
> +
> + mutex_init(&conn->ep_mutex);
> + INIT_LIST_HEAD(&conn->conn_list);
> + INIT_WORK(&conn->cleanup_work, iscsi_cleanup_conn_work_fn);
> + conn->transport = transport;
> + conn->cid = cid;
> + conn->state = ISCSI_CONN_DOWN;
> +
> + /* this is released in the dev's release function */
> + if (!get_device(&session->dev))
> + goto free_conn;
> +
> + dev_set_name(&conn->dev, "connection%d:%u", session->sid, cid);
> + device_initialize(&conn->dev);
> + conn->dev.parent = &session->dev;
> + conn->dev.release = iscsi_conn_release;
> +
> + return conn;
> +
> +free_conn:
> + kfree(conn);
> + return NULL;
> +}
> +EXPORT_SYMBOL_GPL(iscsi_alloc_conn);
> +
> +/**
> + * iscsi_add_conn - add iscsi class connection
> + * @conn: iscsi cls connection
> + *
> + * this would expose iscsi_cls_conn to sysfs, so make sure the related
> + * resources when access sysfs attributes are initialized before calling this.
> + */
> +int iscsi_add_conn(struct iscsi_cls_conn *conn)
> +{
> + int err;
> + unsigned long flags;
> + struct iscsi_cls_session *session = iscsi_dev_to_session(conn->dev.parent);
> +
> + err = device_add(&conn->dev);
> + if (err) {
> + iscsi_cls_session_printk(KERN_ERR, session,
> + "could not register connection's dev\n");
> + put_device(&session->dev);
I would call iscsi_free_conn. instead of put_device.
> + return err;
> + }
> + err = transport_register_device(&conn->dev);
> + if (err) {
> + iscsi_cls_session_printk(KERN_ERR, session,
> + "could not register transport's dev\n");
> + device_del(&conn->dev);
> + put_device(&session->dev);
Is for the get_device(&session->dev) in iscsi_alloc_conn? If so you don't need to
do it because when the last put is done on the conn->dev, it will call
iscsi_conn_release which does the put on the session when it does "put_device(parent).
Or did you mean to call put_device on the conn->dev?
I would do device_el(&conn->dev) then do a goto free_conn at the bottom which
does iscsi_free_conn. The place above should do the goto as well.
> + return err;
> + }
> +
> + spin_lock_irqsave(&connlock, flags);
> + list_add(&conn->conn_list, &connlist);
> + spin_unlock_irqrestore(&connlock, flags);
> +
> + return 0;
> +}
> +EXPORT_SYMBOL_GPL(iscsi_add_conn);
> +
> +/**
> + * iscsi_remove_conn - remove iscsi class connection from sysfs
> + * @conn: iscsi cls connection
> + *
> + * this would remove iscsi_cls_conn from sysfs, and wait for previous
> + * read/write of iscsi_cls_conn's attributes in sysfs finishing
> + */
> +void iscsi_remove_conn(struct iscsi_cls_conn *conn)
> +{
> + device_del(&conn->dev);
This should have the guts of iscsi_destroy_conn which reverses what
the iscsi_add_conn did:
spin_lock_irqsave(&connlock, flags);
list_del(&conn->conn_list);
spin_unlock_irqrestore(&connlock, flags);
transport_unregister_device(&conn->dev);
device_del(&conn->dev).
You can then kill iscsi_destroy_conn.
> +}
> +EXPORT_SYMBOL_GPL(iscsi_remove_conn);
> +
> +void iscsi_free_conn(struct iscsi_cls_conn *conn)
> +{
> + put_device(&conn->dev);
> +}
> +EXPORT_SYMBOL_GPL(iscsi_free_conn);
Sorry I made a mistake with this suggestion. Kill this and just have
the user do iscsi_put_conn.
> +
> /**
> * iscsi_create_conn - create iscsi class connection
> * @session: iscsi cls session
> diff --git a/include/scsi/scsi_transport_iscsi.h b/include/scsi/scsi_transport_iscsi.h
> index c5d7810fd792..346f65bc3861 100644
> --- a/include/scsi/scsi_transport_iscsi.h
> +++ b/include/scsi/scsi_transport_iscsi.h
> @@ -441,6 +441,11 @@ extern struct iscsi_cls_session *iscsi_create_session(struct Scsi_Host *shost,
> unsigned int target_id);
> extern void iscsi_remove_session(struct iscsi_cls_session *session);
> extern void iscsi_free_session(struct iscsi_cls_session *session);
> +extern struct iscsi_cls_conn *iscsi_alloc_conn(struct iscsi_cls_session *sess,
> + int dd_size, uint32_t cid);
> +extern int iscsi_add_conn(struct iscsi_cls_conn *conn);
> +extern void iscsi_remove_conn(struct iscsi_cls_conn *conn);
> +extern void iscsi_free_conn(struct iscsi_cls_conn *conn);
> extern struct iscsi_cls_conn *iscsi_create_conn(struct iscsi_cls_session *sess,
> int dd_size, uint32_t cid);
> extern void iscsi_put_conn(struct iscsi_cls_conn *conn);
On 2022/3/9 1:19, Mike Christie wrote:
> On 3/8/22 9:09 PM, Wenchao Hao wrote:
>> iscsi_alloc_conn(): alloc and initialize iscsi_cls_conn
>> iscsi_add_conn(): expose iscsi_cls_conn to userspace's via sysfs.
>> iscsi_remove_conn(): remove iscsi_cls_conn from sysfs
>> iscsi_free_conn(): free iscsi_cls_conn
>>
>> Signed-off-by: Wenchao Hao <[email protected]>
>> Signed-off-by: Wu Bo <[email protected]>
>> ---
>> drivers/scsi/scsi_transport_iscsi.c | 107 ++++++++++++++++++++++++++++
>> include/scsi/scsi_transport_iscsi.h | 5 ++
>> 2 files changed, 112 insertions(+)
>>
>> diff --git a/drivers/scsi/scsi_transport_iscsi.c b/drivers/scsi/scsi_transport_iscsi.c
>> index 554b6f784223..8e97c6f88359 100644
>> --- a/drivers/scsi/scsi_transport_iscsi.c
>> +++ b/drivers/scsi/scsi_transport_iscsi.c
>> @@ -2340,6 +2340,113 @@ void iscsi_free_session(struct iscsi_cls_session *session)
>> }
>> EXPORT_SYMBOL_GPL(iscsi_free_session);
>>
>> +/**
>> + * iscsi_alloc_conn - alloc iscsi class connection
>> + * @session: iscsi cls session
>> + * @dd_size: private driver data size
>> + * @cid: connection id
>> + *
>> + * This can be called from a LLD or iscsi_transport. The connection
>> + * is child of the session so cid must be unique for all connections
>> + * on the session.
>> + *
>> + * Since we do not support MCS, cid will normally be zero. In some cases
>> + * for software iscsi we could be trying to preallocate a connection struct
>> + * in which case there could be two connection structs and cid would be
>> + * non-zero.
>
> Is that with the upstream iscsi tools or your version? I don't think the comment
> is needed or is needed somewhere else.
>
> If this happens then they will have the same sysfs/device name so when we do the
> device_add it will spit an error about duplicate names.
>
>
>> + */
>> +struct iscsi_cls_conn *
>> +iscsi_alloc_conn(struct iscsi_cls_session *session, int dd_size, uint32_t cid)
>> +{
>> + struct iscsi_transport *transport = session->transport;
>> + struct iscsi_cls_conn *conn;
>> +
>> + conn = kzalloc(sizeof(*conn) + dd_size, GFP_KERNEL);
>> + if (!conn)
>> + return NULL;
>> + if (dd_size)
>> + conn->dd_data = &conn[1];
>> +
>> + mutex_init(&conn->ep_mutex);
>> + INIT_LIST_HEAD(&conn->conn_list);
>> + INIT_WORK(&conn->cleanup_work, iscsi_cleanup_conn_work_fn);
>> + conn->transport = transport;
>> + conn->cid = cid;
>> + conn->state = ISCSI_CONN_DOWN;
>> +
>> + /* this is released in the dev's release function */
>> + if (!get_device(&session->dev))
>> + goto free_conn;
>> +
>> + dev_set_name(&conn->dev, "connection%d:%u", session->sid, cid);
>> + device_initialize(&conn->dev);
>> + conn->dev.parent = &session->dev;
>> + conn->dev.release = iscsi_conn_release;
>> +
>> + return conn;
>> +
>> +free_conn:
>> + kfree(conn);
>> + return NULL;
>> +}
>> +EXPORT_SYMBOL_GPL(iscsi_alloc_conn);
>> +
>> +/**
>> + * iscsi_add_conn - add iscsi class connection
>> + * @conn: iscsi cls connection
>> + *
>> + * this would expose iscsi_cls_conn to sysfs, so make sure the related
>> + * resources when access sysfs attributes are initialized before calling this.
>> + */
>> +int iscsi_add_conn(struct iscsi_cls_conn *conn)
>> +{
>> + int err;
>> + unsigned long flags;
>> + struct iscsi_cls_session *session = iscsi_dev_to_session(conn->dev.parent);
>> +
>> + err = device_add(&conn->dev);
>> + if (err) {
>> + iscsi_cls_session_printk(KERN_ERR, session,
>> + "could not register connection's dev\n");
>> + put_device(&session->dev);
>
> I would call iscsi_free_conn. instead of put_device.
>
Sorry I noticed it but forget to remove it. Here should not call
put_device() or iscsi_free_conn(). If iscsi_add_conn() failed, we shoule
not call any put operation which might cause resource free.
>> + return err;
>> + }
>> + err = transport_register_device(&conn->dev);
>> + if (err) {
>> + iscsi_cls_session_printk(KERN_ERR, session,
>> + "could not register transport's dev\n");
>> + device_del(&conn->dev);
>> + put_device(&session->dev);
>
>
> Is for the get_device(&session->dev) in iscsi_alloc_conn? If so you don't need to
> do it because when the last put is done on the conn->dev, it will call
> iscsi_conn_release which does the put on the session when it does "put_device(parent).
>
> Or did you mean to call put_device on the conn->dev?
>
As above, we shouldn't call put_device() here.
> I would do device_el(&conn->dev) then do a goto free_conn at the bottom which
> does iscsi_free_conn. The place above should do the goto as well.
>
>