[PATCH net-next v2 13/18] net: qede: Remove check of list iterator against head past the loop body

Jakob Koschel
2022-04-12T11:10:05Z

When list_for_each_entry() completes the iteration over the whole list
without breaking the loop, the iterator value will be a bogus pointer
computed based on the head element.

While it is safe to use the pointer to determine if it was computed
based on the head element, either with list_entry_is_head() or
&pos->member == head, using the iterator variable after the loop should
be avoided.

In preparation to limit the scope of a list iterator to the list
traversal loop, use a dedicated pointer to point to the found element [1].

Link: https://lore.kernel.org/all/CAHk-=wgRr_D8CB-D9Kg-c=EHreAsk5SqXPwr9Y7k9sA6cWXJ6w@mail.gmail.com/ [1]
Signed-off-by: Jakob Koschel <jakobkoschel@gmail.com>
---
drivers/net/ethernet/qlogic/qede/qede_filter.c | 11 +++++++----
1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/drivers/net/ethernet/qlogic/qede/qede_filter.c b/drivers/net/ethernet/qlogic/qede/qede_filter.c
index 3010833ddde3..3d167e37e654 100644
--- a/drivers/net/ethernet/qlogic/qede/qede_filter.c
+++ b/drivers/net/ethernet/qlogic/qede/qede_filter.c
@@ -829,18 +829,21 @@ int qede_configure_vlan_filters(struct qede_dev *edev)
int qede_vlan_rx_kill_vid(struct net_device *dev, __be16 proto, u16 vid)
{
struct qede_dev *edev = netdev_priv(dev);
- struct qede_vlan *vlan;
+ struct qede_vlan *vlan = NULL;
+ struct qede_vlan *iter;
int rc = 0;

DP_VERBOSE(edev, NETIF_MSG_IFDOWN, "Removing vlan 0x%04x\n", vid);

/* Find whether entry exists */
__qede_lock(edev);
- list_for_each_entry(vlan, &edev->vlan_list, list)
- if (vlan->vid == vid)
+ list_for_each_entry(iter, &edev->vlan_list, list)
+ if (iter->vid == vid) {
+ vlan = iter;
break;
+ }

- if (list_entry_is_head(vlan, &edev->vlan_list, list)) {
+ if (!vlan) {
DP_VERBOSE(edev, (NETIF_MSG_IFUP | NETIF_MSG_IFDOWN),
"Vlan isn't configured\n");
goto out;