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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org,
        Himanshu Madhani <himanshu.madhani@oracle.com>,
        Javed Hasan <jhasan@marvell.com>,
        "Martin K. Petersen" <martin.petersen@oracle.com>,
        Sasha Levin <sashal@kernel.org>
Subject: [PATCH 5.12 011/127] scsi: qedf: Add pointer checks in qedf_update_link_speed()
Date:   Mon, 24 May 2021 17:25:28 +0200
Message-Id: <20210524152335.237280989@linuxfoundation.org>
In-Reply-To: <20210524152334.857620285@linuxfoundation.org>
References: <20210524152334.857620285@linuxfoundation.org>
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From: Javed Hasan <jhasan@marvell.com>

[ Upstream commit 73578af92a0fae6609b955fcc9113e50e413c80f ]

The following trace was observed:

 [   14.042059] Call Trace:
 [   14.042061]  <IRQ>
 [   14.042068]  qedf_link_update+0x144/0x1f0 [qedf]
 [   14.042117]  qed_link_update+0x5c/0x80 [qed]
 [   14.042135]  qed_mcp_handle_link_change+0x2d2/0x410 [qed]
 [   14.042155]  ? qed_set_ptt+0x70/0x80 [qed]
 [   14.042170]  ? qed_set_ptt+0x70/0x80 [qed]
 [   14.042186]  ? qed_rd+0x13/0x40 [qed]
 [   14.042205]  qed_mcp_handle_events+0x437/0x690 [qed]
 [   14.042221]  ? qed_set_ptt+0x70/0x80 [qed]
 [   14.042239]  qed_int_sp_dpc+0x3a6/0x3e0 [qed]
 [   14.042245]  tasklet_action_common.isra.14+0x5a/0x100
 [   14.042250]  __do_softirq+0xe4/0x2f8
 [   14.042253]  irq_exit+0xf7/0x100
 [   14.042255]  do_IRQ+0x7f/0xd0
 [   14.042257]  common_interrupt+0xf/0xf
 [   14.042259]  </IRQ>

API qedf_link_update() is getting called from QED but by that time
shost_data is not initialised. This results in a NULL pointer dereference
when we try to dereference shost_data while updating supported_speeds.

Add a NULL pointer check before dereferencing shost_data.

Link: https://lore.kernel.org/r/20210512072533.23618-1-jhasan@marvell.com
Fixes: 61d8658b4a43 ("scsi: qedf: Add QLogic FastLinQ offload FCoE driver framework.")
Reviewed-by: Himanshu Madhani <himanshu.madhani@oracle.com>
Signed-off-by: Javed Hasan <jhasan@marvell.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/scsi/qedf/qedf_main.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/scsi/qedf/qedf_main.c b/drivers/scsi/qedf/qedf_main.c
index cec27f2ef70d..e5076f09d5ed 100644
--- a/drivers/scsi/qedf/qedf_main.c
+++ b/drivers/scsi/qedf/qedf_main.c
@@ -536,7 +536,9 @@ static void qedf_update_link_speed(struct qedf_ctx *qedf,
 	if (linkmode_intersects(link->supported_caps, sup_caps))
 		lport->link_supported_speeds |= FC_PORTSPEED_20GBIT;
 
-	fc_host_supported_speeds(lport->host) = lport->link_supported_speeds;
+	if (lport->host && lport->host->shost_data)
+		fc_host_supported_speeds(lport->host) =
+			lport->link_supported_speeds;
 }
 
 static void qedf_bw_update(void *dev)
-- 
2.30.2