netdev - [PATCH net 2/2] bnxt_en: Fix NULL ptr dereference crash in bnxt_fw_reset

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Date:   Sat,  5 Sep 2020 22:55:37 -0400
From:   Michael Chan <michael.chan@...adcom.com>
To:     davem@...emloft.net
Cc:     netdev@...r.kernel.org, kuba@...nel.org,
        Vasundhara Volam <vasundhara-v.volam@...adcom.com>
Subject: [PATCH net 2/2] bnxt_en: Fix NULL ptr dereference crash in bnxt_fw_reset_task()

From: Vasundhara Volam <vasundhara-v.volam@...adcom.com>

bnxt_fw_reset_task() which runs from a workqueue can race with
bnxt_remove_one().  For example, if firmware reset and VF FLR are
happening at about the same time.

bnxt_remove_one() already cancels the workqueue and waits for it
to finish, but we need to do this earlier before the devlink
reporters are destroyed.  This will guarantee that
the devlink reporters will always be valid when bnxt_fw_reset_task()
is still running.

Fixes: b148bb238c02 ("bnxt_en: Fix possible crash in bnxt_fw_reset_task().")
Reviewed-by: Edwin Peer <edwin.peer@...adcom.com>
Signed-off-by: Vasundhara Volam <vasundhara-v.volam@...adcom.com>
Signed-off-by: Michael Chan <michael.chan@...adcom.com>
---
 drivers/net/ethernet/broadcom/bnxt/bnxt.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/drivers/net/ethernet/broadcom/bnxt/bnxt.c b/drivers/net/ethernet/broadcom/bnxt/bnxt.c
index 619eb55..8eb73fe 100644
--- a/drivers/net/ethernet/broadcom/bnxt/bnxt.c
+++ b/drivers/net/ethernet/broadcom/bnxt/bnxt.c
@@ -11779,6 +11779,10 @@ static void bnxt_remove_one(struct pci_dev *pdev)
 	if (BNXT_PF(bp))
 		bnxt_sriov_disable(bp);
 
+	clear_bit(BNXT_STATE_IN_FW_RESET, &bp->state);
+	bnxt_cancel_sp_work(bp);
+	bp->sp_event = 0;
+
 	bnxt_dl_fw_reporters_destroy(bp, true);
 	if (BNXT_PF(bp))
 		devlink_port_type_clear(&bp->dl_port);
@@ -11786,9 +11790,6 @@ static void bnxt_remove_one(struct pci_dev *pdev)
 	unregister_netdev(dev);
 	bnxt_dl_unregister(bp);
 	bnxt_shutdown_tc(bp);
-	clear_bit(BNXT_STATE_IN_FW_RESET, &bp->state);
-	bnxt_cancel_sp_work(bp);
-	bp->sp_event = 0;
 
 	bnxt_clear_int_mode(bp);
 	bnxt_hwrm_func_drv_unrgtr(bp);
-- 
1.8.3.1