[PATCH AUTOSEL 5.15 06/12] scsi: iscsi_tcp: Fix UAF during login when accessing the shost ipaddress

Sasha Levin
2023-01-31T15:03:05Z

From: Mike Christie <michael.christie@oracle.com>

[ Upstream commit f484a794e4ee2a9ce61f52a78e810ac45f3fe3b3 ]

If during iscsi_sw_tcp_session_create() iscsi_tcp_r2tpool_alloc() fails,
userspace could be accessing the host's ipaddress attr. If we then free the
session via iscsi_session_teardown() while userspace is still accessing the
session we will hit a use after free bug.

Set the tcp_sw_host->session after we have completed session creation and
can no longer fail.

Link: https://lore.kernel.org/r/20230117193937.21244-3-michael.christie@oracle.com
Signed-off-by: Mike Christie <michael.christie@oracle.com>
Reviewed-by: Lee Duncan <lduncan@suse.com>
Acked-by: Ding Hui <dinghui@sangfor.com.cn>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/scsi/iscsi_tcp.c | 9 ++++++---
1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/drivers/scsi/iscsi_tcp.c b/drivers/scsi/iscsi_tcp.c
index 5c19e75c0e2f..594336004190 100644
--- a/drivers/scsi/iscsi_tcp.c
+++ b/drivers/scsi/iscsi_tcp.c
@@ -848,7 +848,7 @@ static int iscsi_sw_tcp_host_get_param(struct Scsi_Host *shost,
enum iscsi_host_param param, char *buf)
{
struct iscsi_sw_tcp_host *tcp_sw_host = iscsi_host_priv(shost);
- struct iscsi_session *session = tcp_sw_host->session;
+ struct iscsi_session *session;
struct iscsi_conn *conn;
struct iscsi_tcp_conn *tcp_conn;
struct iscsi_sw_tcp_conn *tcp_sw_conn;
@@ -858,6 +858,7 @@ static int iscsi_sw_tcp_host_get_param(struct Scsi_Host *shost,

switch (param) {
case ISCSI_HOST_PARAM_IPADDRESS:
+ session = tcp_sw_host->session;
if (!session)
return -ENOTCONN;

@@ -958,11 +959,13 @@ iscsi_sw_tcp_session_create(struct iscsi_endpoint *ep, uint16_t cmds_max,
if (!cls_session)
goto remove_host;
session = cls_session->dd_data;
- tcp_sw_host = iscsi_host_priv(shost);
- tcp_sw_host->session = session;

if (iscsi_tcp_r2tpool_alloc(session))
goto remove_session;
+
+ /* We are now fully setup so expose the session to sysfs. */
+ tcp_sw_host = iscsi_host_priv(shost);
+ tcp_sw_host->session = session;
return cls_session;

remove_session:
--
2.39.0