[PATCH 4.14 223/284] scsi: libfc: Fix use after free in fc_exch_abts_resp()

Greg Kroah-Hartman
2022-04-18T13:57:34Z

From: Jianglei Nie <niejianglei2021@163.com>

[ Upstream commit 271add11994ba1a334859069367e04d2be2ebdd4 ]

fc_exch_release(ep) will decrease the ep's reference count. When the
reference count reaches zero, it is freed. But ep is still used in the
following code, which will lead to a use after free.

Return after the fc_exch_release() call to avoid use after free.

Link: https://lore.kernel.org/r/20220303015115.459778-1-niejianglei2021@163.com
Reviewed-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: Jianglei Nie <niejianglei2021@163.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/scsi/libfc/fc_exch.c | 1 +
1 file changed, 1 insertion(+)

diff --git a/drivers/scsi/libfc/fc_exch.c b/drivers/scsi/libfc/fc_exch.c
index 384458d1f73c..9fa0aa235cb4 100644
--- a/drivers/scsi/libfc/fc_exch.c
+++ b/drivers/scsi/libfc/fc_exch.c
@@ -1709,6 +1709,7 @@ static void fc_exch_abts_resp(struct fc_exch *ep, struct fc_frame *fp)
if (cancel_delayed_work_sync(&ep->timeout_work)) {
FC_EXCH_DBG(ep, "Exchange timer canceled due to ABTS response\n");
fc_exch_release(ep); /* release from pending timer hold */
+ return;
}

spin_lock_bh(&ep->ex_lock);
--
2.35.1