[PATCH 3.16 153/328] iscsi target: fix session creation failure handling

Ben Hutchings
2018-12-09T22:08:37Z

From: Mike Christie <mchristi@redhat.com>

commit 26abc916a898d34c5ad159315a2f683def3c5555 upstream.

The problem is that iscsi_login_zero_tsih_s1 sets conn->sess early in
iscsi_login_set_conn_values. If the function fails later like when we
alloc the idr it does kfree(sess) and leaves the conn->sess pointer set.
iscsi_login_zero_tsih_s1 then returns -Exyz and we then call
iscsi_target_login_sess_out and access the freed memory.

This patch has iscsi_login_zero_tsih_s1 either completely setup the
session or completely tear it down, so later in
iscsi_target_login_sess_out we can just check for it being set to the
connection.

Fixes: 0957627a9960 ("iscsi-target: Fix sess allocation leak in...")
Signed-off-by: Mike Christie <mchristi@redhat.com>
Acked-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Matthew Wilcox <willy@infradead.org>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
drivers/target/iscsi/iscsi_target_login.c | 35 ++++++++++++++---------
1 file changed, 21 insertions(+), 14 deletions(-)

--- a/drivers/target/iscsi/iscsi_target_login.c
+++ b/drivers/target/iscsi/iscsi_target_login.c
@@ -323,8 +323,7 @@ static int iscsi_login_zero_tsih_s1(
pr_err("idr_alloc() for sess_idr failed\n");
iscsit_tx_login_rsp(conn, ISCSI_STATUS_CLS_TARGET_ERR,
ISCSI_LOGIN_STATUS_NO_RESOURCES);
- kfree(sess);
- return -ENOMEM;
+ goto free_sess;
}

sess->creation_time = get_jiffies_64();
@@ -340,20 +339,28 @@ static int iscsi_login_zero_tsih_s1(
ISCSI_LOGIN_STATUS_NO_RESOURCES);
pr_err("Unable to allocate memory for"
" struct iscsi_sess_ops.\n");
- kfree(sess);
- return -ENOMEM;
+ goto remove_idr;
}

sess->se_sess = transport_init_session(TARGET_PROT_NORMAL);
if (IS_ERR(sess->se_sess)) {
iscsit_tx_login_rsp(conn, ISCSI_STATUS_CLS_TARGET_ERR,
ISCSI_LOGIN_STATUS_NO_RESOURCES);
- kfree(sess->sess_ops);
- kfree(sess);
- return -ENOMEM;
+ goto free_ops;
}

return 0;
+
+free_ops:
+ kfree(sess->sess_ops);
+remove_idr:
+ spin_lock_bh(&sess_idr_lock);
+ idr_remove(&sess_idr, sess->session_index);
+ spin_unlock_bh(&sess_idr_lock);
+free_sess:
+ kfree(sess);
+ conn->sess = NULL;
+ return -ENOMEM;
}

static int iscsi_login_zero_tsih_s2(
@@ -1201,13 +1208,13 @@ void iscsi_target_login_sess_out(struct
ISCSI_LOGIN_STATUS_INIT_ERR);
if (!zero_tsih || !conn->sess)
goto old_sess_out;
- if (conn->sess->se_sess)
- transport_free_session(conn->sess->se_sess);
- if (conn->sess->session_index != 0) {
- spin_lock_bh(&sess_idr_lock);
- idr_remove(&sess_idr, conn->sess->session_index);
- spin_unlock_bh(&sess_idr_lock);
- }
+
+ transport_free_session(conn->sess->se_sess);
+
+ spin_lock_bh(&sess_idr_lock);
+ idr_remove(&sess_idr, conn->sess->session_index);
+ spin_unlock_bh(&sess_idr_lock);
+
kfree(conn->sess->sess_ops);
kfree(conn->sess);
conn->sess = NULL;