linux-kernel - [PATCH AUTOSEL 4.19 2/4] scsi: iscsi_tcp: Fix UAF during login when accessing the shost ipaddress

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Message-Id: <20230131150118.1250409-2-sashal@kernel.org>
Date:   Tue, 31 Jan 2023 10:01:16 -0500
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Mike Christie <michael.christie@...cle.com>,
        Lee Duncan <lduncan@...e.com>,
        Ding Hui <dinghui@...gfor.com.cn>,
        "Martin K . Petersen" <martin.petersen@...cle.com>,
        Sasha Levin <sashal@...nel.org>, cleech@...hat.com,
        jejb@...ux.ibm.com, open-iscsi@...glegroups.com,
        linux-scsi@...r.kernel.org
Subject: [PATCH AUTOSEL 4.19 2/4] scsi: iscsi_tcp: Fix UAF during login when accessing the shost ipaddress

From: Mike Christie <michael.christie@...cle.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@...cle.com>
Reviewed-by: Lee Duncan <lduncan@...e.com>
Acked-by: Ding Hui <dinghui@...gfor.com.cn>
Signed-off-by: Martin K. Petersen <martin.petersen@...cle.com>
Signed-off-by: Sasha Levin <sashal@...nel.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 7212e3a13fe6..33fb111e2e19 100644
--- a/drivers/scsi/iscsi_tcp.c
+++ b/drivers/scsi/iscsi_tcp.c
@@ -775,7 +775,7 @@ 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;
@@ -784,6 +784,7 @@ 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;
 
@@ -872,12 +873,14 @@ 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;
 
 	shost->can_queue = session->scsi_cmds_max;
 	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