i40e: i40e_main: fix a missing check on list iterator

The bug is here:
	ret = i40e_add_macvlan_filter(hw, ch->seid, vdev->dev_addr, &aq_err);

The list iterator 'ch' will point to a bogus position containing
HEAD if the list is empty or no element is found. This case must
be checked before any use of the iterator, otherwise it will
lead to a invalid memory access.

To fix this bug, use a new variable 'iter' as the list iterator,
while use the origin variable 'ch' as a dedicated pointer to
point to the found element.

Cc: stable@vger.kernel.org
Fixes: 1d8d80b4e4ff6 ("i40e: Add macvlan support on i40e")
Signed-off-by: Xiaomeng Tong <xiam0nd.tong@gmail.com>
Tested-by: Gurucharan <gurucharanx.g@intel.com> (A Contingent worker at Intel)
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>
Link: https://lore.kernel.org/r/20220510204846.2166999-1-anthony.l.nguyen@intel.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/drivers/net/ethernet/intel/i40e/i40e_main.c b/drivers/net/ethernet/intel/i40e/i40e_main.c
index 6778df2177a114a63114b9709610d3bdddc73778..98871f01499469332b03b38a278e89d1532ccff0 100644 (file)
--- a/drivers/net/ethernet/intel/i40e/i40e_main.c
+++ b/drivers/net/ethernet/intel/i40e/i40e_main.c
@@ -7549,42 +7549,43 @@ static void i40e_free_macvlan_channels(struct i40e_vsi *vsi)
 static int i40e_fwd_ring_up(struct i40e_vsi *vsi, struct net_device *vdev,
                            struct i40e_fwd_adapter *fwd)
 {
+       struct i40e_channel *ch = NULL, *ch_tmp, *iter;
        int ret = 0, num_tc = 1,  i, aq_err;
-       struct i40e_channel *ch, *ch_tmp;
        struct i40e_pf *pf = vsi->back;
        struct i40e_hw *hw = &pf->hw;
 
-       if (list_empty(&vsi->macvlan_list))
-               return -EINVAL;
-
        /* Go through the list and find an available channel */
-       list_for_each_entry_safe(ch, ch_tmp, &vsi->macvlan_list, list) {
-               if (!i40e_is_channel_macvlan(ch)) {
-                       ch->fwd = fwd;
+       list_for_each_entry_safe(iter, ch_tmp, &vsi->macvlan_list, list) {
+               if (!i40e_is_channel_macvlan(iter)) {
+                       iter->fwd = fwd;
                        /* record configuration for macvlan interface in vdev */
                        for (i = 0; i < num_tc; i++)
                                netdev_bind_sb_channel_queue(vsi->netdev, vdev,
                                                             i,
-                                                            ch->num_queue_pairs,
-                                                            ch->base_queue);
-                       for (i = 0; i < ch->num_queue_pairs; i++) {
+                                                            iter->num_queue_pairs,
+                                                            iter->base_queue);
+                       for (i = 0; i < iter->num_queue_pairs; i++) {
                                struct i40e_ring *tx_ring, *rx_ring;
                                u16 pf_q;
 
-                               pf_q = ch->base_queue + i;
+                               pf_q = iter->base_queue + i;
 
                                /* Get to TX ring ptr */
                                tx_ring = vsi->tx_rings[pf_q];
-                               tx_ring->ch = ch;
+                               tx_ring->ch = iter;
 
                                /* Get the RX ring ptr */
                                rx_ring = vsi->rx_rings[pf_q];
-                               rx_ring->ch = ch;
+                               rx_ring->ch = iter;
                        }
+                       ch = iter;
                        break;
                }
        }
 
+       if (!ch)
+               return -EINVAL;
+
        /* Guarantee all rings are updated before we update the
         * MAC address filter.
         */