linux-kernel - [PATCH] scsi: qla4xxx: Fix a potential race condition.

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Date:   Tue, 21 Apr 2020 16:08:22 -0500
From:   wu000273@....edu
To:     jejb@...ux.ibm.com
Cc:     QLogic-Storage-Upstream@...gic.com, martin.petersen@...cle.com,
        linux-scsi@...r.kernel.org, linux-kernel@...r.kernel.org,
        kjlu@....edu, wu000273@....edu
Subject: [PATCH] scsi: qla4xxx: Fix a potential race condition.

From: Qiushi Wu <wu000273@....edu>

In the function qla4xxx_eh_abort, we should use lock protect both
kref_get() and kref_put(), because we must serialize access where a
kref_put() cannot occur during the kref_get(). Otherwise, the object
"srb" may not remain valid during the kref_get(), and a race condition
can happen.

Signed-off-by: Qiushi Wu <wu000273@....edu>
---
 drivers/scsi/qla4xxx/ql4_os.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/scsi/qla4xxx/ql4_os.c b/drivers/scsi/qla4xxx/ql4_os.c
index 5504ab11decc..a1400cadb91a 100644
--- a/drivers/scsi/qla4xxx/ql4_os.c
+++ b/drivers/scsi/qla4xxx/ql4_os.c
@@ -9222,8 +9222,10 @@ static int qla4xxx_eh_abort(struct scsi_cmnd *cmd)
 		    ha->host_no, id, lun));
 		wait = 1;
 	}
-
+
+	spin_lock_irqsave(&ha->hardware_lock, flags);
 	kref_put(&srb->srb_ref, qla4xxx_srb_compl);
+	spin_unlock_irqrestore(&ha->hardware_lock, flags);
 
 	/* Wait for command to complete */
 	if (wait) {
-- 
2.17.1