[PATCH net 2/8] i40e: avoid null ptr dereference in i40e_ptp_stop()

[Tony Nguyen <anthony.l.nguyen@intel.com>]

From: Maciej Fijalkowski <maciej.fijalkowski@intel.com>

Sashiko reports:
***
If an allocation fails here during i40e_rebuild(), i40e_vsi_clear()
frees the
main VSI and sets pf->vsi[vsi->idx] = NULL, and the rebuild will abort
without
stopping the PTP clock.
Later, if the device is removed or unbound, i40e_remove()
unconditionally
calls i40e_ptp_stop(), which does:
drivers/net/ethernet/intel/i40e/i40e_ptp.c:i40e_ptp_stop() {
    ...
	struct i40e_vsi *main_vsi = i40e_pf_get_main_vsi(pf);
    ...
	dev_info(&pf->pdev->dev, "%s: removed PHC on %s\n", __func__,
		 main_vsi->netdev->name);
    ...
}
Would this cause a NULL pointer dereference since main_vsi is now NULL?
***

Check if main_vsi is not null before calling dev_info().

Fixes: beb0dff1251d ("i40e: enable PTP")
Reported-by: Sashiko AI Review <sashiko-bot@kernel.org>
Signed-off-by: Maciej Fijalkowski <maciej.fijalkowski@intel.com>
Reviewed-by: Aleksandr Loktionov <aleksandr.loktionov@intel.com>
Tested-by: Sunitha Mekala <sunithax.d.mekala@intel.com> (A Contingent worker at Intel)
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>
---
 drivers/net/ethernet/intel/i40e/i40e_ptp.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/net/ethernet/intel/i40e/i40e_ptp.c b/drivers/net/ethernet/intel/i40e/i40e_ptp.c
index ff62b5f2c815..ca93df4d6785 100644
--- a/drivers/net/ethernet/intel/i40e/i40e_ptp.c
+++ b/drivers/net/ethernet/intel/i40e/i40e_ptp.c
@@ -1556,8 +1556,9 @@ void i40e_ptp_stop(struct i40e_pf *pf)
 	if (pf->ptp_clock) {
 		ptp_clock_unregister(pf->ptp_clock);
 		pf->ptp_clock = NULL;
-		dev_info(&pf->pdev->dev, "%s: removed PHC on %s\n", __func__,
-			 main_vsi->netdev->name);
+		if (main_vsi)
+			dev_info(&pf->pdev->dev, "%s: removed PHC on %s\n", __func__,
+				 main_vsi->netdev->name);
 	}
 
 	if (i40e_is_ptp_pin_dev(&pf->hw)) {
-- 
2.47.1