[SRU][Jammy-OEM-5.17/OEM-6.0][PATCH 1/1] scsi: iscsi_tcp: Fix UAF during login when accessing the shost ipaddress

Yuxuan Luo yuxuan.luo at canonical.com
Mon Jul 31 18:28:02 UTC 2023

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

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 at oracle.com>
Reviewed-by: Lee Duncan <lduncan at suse.com>
Acked-by: Ding Hui <dinghui at sangfor.com.cn>
Signed-off-by: Martin K. Petersen <martin.petersen at oracle.com>
(cherry picked from commit f484a794e4ee2a9ce61f52a78e810ac45f3fe3b3)
Signed-off-by: Yuxuan Luo <yuxuan.luo at canonical.com>
 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 5fb1f364e815..f3434a029558 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) {
+		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;

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