[PATCH AUTOSEL 4.14 05/13] net: Catch invalid index in XPS mapping

[Sasha Levin]

From: Nick Child <nnac123@xxxxxxxxxxxxx>

[ Upstream commit 5dd0dfd55baec0742ba8f5625a0dd064aca7db16 ]

When setting the XPS value of a TX queue, warn the user once if the
index of the queue is greater than the number of allocated TX queues.

Previously, this scenario went uncaught. In the best case, it resulted
in unnecessary allocations. In the worst case, it resulted in
out-of-bounds memory references through calls to `netdev_get_tx_queue(
dev, index)`. Therefore, it is important to inform the user but not
worth returning an error and risk downing the netdevice.

Signed-off-by: Nick Child <nnac123@xxxxxxxxxxxxx>
Reviewed-by: Piotr Raczynski <piotr.raczynski@xxxxxxxxx>
Link: https://lore.kernel.org/r/20230321150725.127229-1-nnac123@xxxxxxxxxxxxx
Signed-off-by: Jakub Kicinski <kuba@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 net/core/dev.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/net/core/dev.c b/net/core/dev.c
index 86f762a1cf7ac..a4d68da682322 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -2165,6 +2165,8 @@ int netif_set_xps_queue(struct net_device *dev, const struct cpumask *mask,
 	struct xps_map *map, *new_map;
 	bool active = false;
 
+	WARN_ON_ONCE(index >= dev->num_tx_queues);
+
 	if (dev->num_tc) {
 		num_tc = dev->num_tc;
 		tc = netdev_txq_to_tc(dev, index);
-- 
2.39.2